It expresses an action or state without reference to any subject. It can be the source of sentence fragments when the writer mistakenly thinks the infinitive form is a fully-functioning verb.

When we speak of the English infinitive, we usually mean the basic form of the verb with “to” in front of it: to go, to sing, to walk, to speak.

Verbs said to be in the infinitive mood can include participle forms ending in -ed and -ing. Verbs in the infinitive mood are not being used as verbs, but as other parts of speech:

To err is human; to forgive, divine. Here, to err and to forgive are used as nouns.

He is a man to be admired. Here, to be admired is an adjective, the equivalent ofadmirable. It describes the noun man.

He came to see you. Here, to see you is used as an adverb to tell why he came.

Source: http//Source http://www.dailywritingtips.com/english-grammar-101-verb-mood/

Future progressive tense is used to indicate action which will be taking place at some time in the future.

For example,

I will be singing at Symphony Hall next month.

We'll be leaving next Monday.

When you arrive, I'll be cooking dinner.

The future progressive tense is formed by adding will be to the ?ing form of the main verb.

She will be coming around the mountain in a few minutes.

She'll be riding a white horse into town.

The future progressive tense is not as common as other tenses, and it can some-times be replaced by simple future, present progressive or even simple present.

I'll be leaving in a few minutes.

I'll leave in a few minutes.

I'm going to leave in a few minutes.

I'm leaving in a few minutes.

I leave in a few minutes.

We use the present continuous to talk about things that we have already arranged to do in the future.

I've got my ticket. I'm leaving on Thursday.

I'm seeing Julie at 5 and then I'm having dinner with Simon.

He's picking me up at the airport.

The company is giving everyone a bonus for Christmas.

In many situations when we talk about future plans we can use either the present continuous or the 'going to' future. However, when we use the present continuous, there is more of a suggestion that an arrangement has already been made.

I'm going to see him./I'm seeing him.

I'm going to do it./I'm doing it.

We use the present simple to talk about events in the future which are 'timetabled'. We can also use the present continuous to talk about these.

My plane leaves at 6 in the morning.

The shop opens at 9.30.

The sun rises a minute earlier tomorrow.

My plane is leaving at 8.30.

The shop is closing at 7.00.

The sun is rising at 6.32 tomorrow.

Like Simple Future, Future in the Past has two different forms in English: "would" and "was going to." Although the two forms can sometimes be used interchangeably, they often express two different meanings.

FORM Would

[would + VERB]

FORM Was/Were Going To

[was/were + going to + VERB]

USE 1 Future in Past

Future in the Past is used to express the idea that in the past you thought something would happen in the future. It does not matter if you are correct or not. Future in the Past follows the same basic rules as the Simple Future. "Would" is used to volunteer or promise, and "was going to" is used to plan. Moreover, both forms can be used to make predictions about the future.

REMEMBER No Future in Time Clauses

Like all future forms, Future in the Past cannot be used in clauses beginning with time expressions such as: when, while, before, after, by the time, as soon as, if, unless, etc. Instead of using Future in the Past, you must use Simple Past.

ACTIVE / PASSIVE

Future Perfect Continuous has two different forms: "will have been doing " and "be going to have been doing." Unlike Simple Future forms, Future Perfect Continuous forms are usually interchangeable.

FORM Future Perfect Continuous with "Will"

[will have been + present participle]

FORM Future Perfect Continuous with "Be Going To"

[am/is/are + going to have been + present participle]

NOTE: It is possible to use either "will" or "be going to" to create the Future Perfect Continuous with little or no difference in meaning.

Complete List of Future Perfect Continuous Forms

USE 1 Duration Before Something in the Future

We use the Future Perfect Continuous to show that something will continue up until a particular event or time in the future. "For five minutes," "for two weeks," and "since Friday" are all durations which can be used with the Future Perfect Continuous. Notice that this is related to the Present Perfect Continuous and the Past Perfect Continuous; however, with Future Perfect Continuous, the duration stops at or before a reference point in the future.

Notice in the examples above that the reference points (marked in italics) are in Simple Present rather than Simple Future. This is because these future events are in time clauses, and you cannot use future tenses in time clauses.

USE 2 Cause of Something in the Future

Using the Future Perfect Continuous before another action in the future is a good way to show cause and effect.

Future Continuous vs. Future Perfect Continuous

If you do not include a duration such as "for five minutes," "for two weeks" or "since Friday," many English speakers choose to use the Future Continuous rather than the Future Perfect Continuous. Be careful because this can change the meaning of the sentence. Future Continuous emphasizes interrupted actions, whereas Future Perfect Continuous emphasizes a duration of time before something in the future. Study the examples below to understand the difference.

REMEMBER No Future in Time Clauses

Like all future forms, the Future Perfect Continuous cannot be used in clauses beginning with time expressions such as: when, while, before, after, by the time, as soon as, if, unless, etc. Instead of Future Perfect Continuous, Present Perfect Continuous is used.

AND REMEMBER Non-Continuous Verbs / Mixed Verbs

It is important to remember that Non-Continuous Verbs cannot be used in any continuous tenses. Also, certain non-continuous meanings for Mixed Verbs cannot be used in continuous tenses. Instead of using Future Perfect Continuous with these verbs, you must use Future Perfect .

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.

ACTIVE / PASSIVE

NOTE: Passive forms of the Future Perfect Continuous are not common.

Source: http://www.englishpage.com/verbpage/futureperfectcontinuous.html

Future Perfect has two different forms: "will have done" and "be going to have done." Unlike Simple Future forms, Future Perfect forms are usually interchangeable.

FORM Future Perfect with "Will"

[will have + past participle]

FORM Future Perfect with "Be Going To"

[am/is/are + going to have + past participle]

NOTE: It is possible to use either "will" or "be going to" to create the Future Perfect with little or no difference in meaning.

Complete List of Future Perfect Forms

USE 1 Completed Action Before Something in the Future

The Future Perfect expresses the idea that something will occur before another action in the future. It can also show that something will happen before a specific time in the future.

Notice in the examples above that the reference points (marked in italics) are in Simple Present rather than Simple Future. This is because the interruptions are in time clauses, and you cannot use future tenses in time clauses.

USE 2 Duration Before Something in the Future (Non-Continuous Verbs)

With Non-Continuous Verbs and some non-continuous uses of Mixed Verbs, we use the Future Perfect to show that something will continue up until another action in the future.

Although the above use of Future Perfect is normally limited to Non-Continuous Verbs and non-continuous uses of Mixed Verbs, the words "live," "work," "teach," and "study" are sometimes used in this way even though they are NOT Non-Continuous Verbs.

REMEMBER No Future in Time Clauses

Like all future forms, the Future Perfect cannot be used in clauses beginning with time expressions such as: when, while, before, after, by the time, as soon as, if, unless, etc. Instead of Future Perfect, Present Perfect is used.

ADVERB PLACEMENT

The examples below show the placement for grammar adverbs such as: always, only, never, ever, still, just, etc.

ACTIVE / PASSIVE

There is no one 'future tense' in English. There are 4 future forms. The one which is used most often in spoken English is 'going to', not 'will'.

We use 'going to' when we want to talk about a plan for the future.

I'm going to see him later today.

They're going to launch it next month.

We're going to have lunch first.

She's going to see what she can do.

I'm not going to talk for very long.

Notice that this plan does not have to be for the near future.

When I retire I'm going to go back to Barbados to live.

In ten years time, I'm going to be boss of my own successful company.

We use 'going to' when we want to make a prediction based on evidence we can see now.

Look out! That cup is going to fall off.

Look at those black clouds. It's going to rain soon.

These figures are really bad. We're going to make a loss.

You look very tired. You're going to need to stop soon.

We can replace 'going to go' by 'going'.

I'm going out later.

She's going to the exhibition tomorrow.

Some people have been taught that 'will' is 'the future' in English. This is not correct. Sometimes when we talk about the future we cannot use 'will'. Sometimes when we use 'will' we are not talking about the future.

We can use 'will' to talk about future events we believe to be certain.

· The sun will rise over there tomorrow morning.

· Next year, I'll be 50.

· That plane will be late. It always is.

· There won't be any snow. I'm certain. It's too warm.

Often we add 'perhaps', 'maybe', 'probably', 'possibly' to make the belief less certain.

· I'll probably come back later.

· He'll possibly find out when he sees Jenny.

· Maybe it will be OK.

· Perhaps we'll meet again some day.

We often use 'will' with 'I think' or 'I hope'.

· I think I'll go to bed now.

· I think she'll do well in the job.

· I hope you'll enjoy your stay.

· I hope you won't make too much noise.

We use 'will' at the moment we make a new decision or plan. The thought has just come into our head.

· Bye. I'll phone you when I get there.

· I'll answer that.

· I'll go.

· I won't tell him. I promise.

We use the past perfect continuous to look back at a situation in progress.

· It was a good time to invest. Inflation had been falling for several months.

· Before I changed jobs, I had been working on a plan to reduce production costs.

· We had been thinking about buying a new house but then we decided to stay here.

We use it to say what had been happening before something else happened.

· It had been snowing for a while before we left.

· We had been playing tennis for only a few minutes when it started raining.

· He was out of breath when he arrived because he had been running.

We use it when reporting things said in the past.

· She said she had been trying to call me all day.

· They said they had been shopping.

· I told you I had been looking for some new clothes.

We use the past perfect simple to talk about what happened before a point in the past. It looks back from a point in the past to further in the past.

· I hadn't known the bad news when I spoke to him.

· I checked with the supplier and they still hadn't received the contract.

· She had already told him before I got a chance to give him my version.

· The company has started the year well but was badly hit by the postal strike.

The past perfect simple is often used when we report what people had said/thought/believed.

· He told me they had already paid the bill.

· He said he believed that John had moved to Italy.

· I thought we had already decided on a name for this product.

We use the past simple to talk about actions and states which we see as completed in the past.

We can use it to talk about a specific point in time.
We use the past continuous to talk about past events which went on for a period of time.

We use it when we want to emphasize the continuing process of an activity or the period of that activity. (If we just want to talk about the past event as a simple fact, we use the past simple.)

· While I was driving home, Peter was trying desperately to contact me.

· Were you expecting any visitors?

· Sorry, were you sleeping?

· I was just making some coffee.

· I was thinking about him last night.

· In the 1990s few people were using mobile phones.

We often use it to describe a "background action" when something else happened.

· I was walking in the street when I suddenly fell over.

· She was talking to me on the phone and it suddenly went dead.

· They were still waiting for the plane when I spoke to them.

· The company was declining rapidly before he took charge.

· We were just talking about it before you arrived.

· I was making a presentation in front of 500 people when the microphone stopped working.

We use the past simple to talk about actions and states which we see as completed in the past.

We can use it to talk about a specific point in time.

· She came back last Friday.

· I saw her in the street.

· They didn't agree to the deal.

It can also be used to talk about a period of time.

· She lived in Tokyo for seven years.

· They were in London from Monday to Thursday of last week.

· When I was living in New York, I went to all the art exhibitions I could.

You will often find the past simple used with time expressions such as these:

· Yesterday

· three weeks ago

· last year

· in 2002

· from March to June

· for a long time

· for 6 weeks

· in the 1980s

· in the last century

· in the past

This tense is used to talk about an action or actions that started in the past and continued until recently or that continue into the future:
We can use it to refer to an action that has finished but you can still see evidence.

· Oh, the kitchen is a mess. Who has been cooking?

· You look tired. Have you been sleeping properly?

· I've got a a stiff neck. I've been working too long on computer.

It can refer to an action that has not finished.

· I've been learning Spanish for 20 years and I still don't know very much.

· I've been waiting for him for 30 minutes and he still hasn't arrived.

· He's been telling me about it for days. I wish he would stop.

It can refer to a series of actions.

· She's been writing to her regularly for a couple of years.

· He's been phoning me all week for an answer.

· The university has been sending students here for over twenty years to do work experience.

The present perfect continuous is often used with 'since', 'for', 'all week', 'for days', 'lately', 'recently', 'over the last few months'.

· I've been wanting to do that for ten years.

· You haven't been getting good results over the last few months.

· They haven't been working all week. They're on strike

· He hasn't been talking to me for weeks.

· We've been working hard on it for ages.

· I've been looking at other options recently.

· He's been working here since 2001.

(Please note that British and American English have different rules for the use of this tense. The explanation and exercises here refer to British English. In American English, it is often acceptable to use the past simple in some of these examples.)
We use the present perfect when we want to look back from the present to the past.
We can use it to look back on the recent past.

I've broken my watch so I don't know what time it is.

They have cancelled the meeting.

She's taken my copy. I don't have one.

The sales team has doubled its turnover.

When we look back on the recent past, we often use the words 'just' 'already' or the word 'yet' (in negatives and questions only).

We've already talked about that.

She hasn't arrived yet.

I've just done it.

They've already met.

They don't know yet.

Have you spoken to him yet?

Have they got back to you yet?

It can also be used to look back on the more distant past.

We've been to Singapore a lot over the last few years.

She's done this type of project many times before.

We've mentioned it to them on several occasions over the last six months.

They've often talked about it in the past.

When we look back on the more distant past, we often use the words 'ever' (in questions) and 'never'.

Have you ever been to Argentina?

Has he ever talked to you about the problem?

I've never met Jim and Sally.

We've never considered investing in Mexico.