FUTURE PERFECT: GENERAL APPROACH

In English grammar, the word 'perfect' means past or finished.  Therefore, the future perfect indicates something in the future will be finished BEFORE another event.

This verbal tense has both simple and progressive (or continuous) forms, and refers to time which we look back at from a future point. Look at these two examples:

FUTURE PERFECT SIMPLE:
In two year's time I'll have finished this book.

FUTURE PERFECT PROGRESSIVE:
By the end of the month, I'll have been working for this firm for a year.

The future perfect progressive can also be used to express an assumption on the part of the speaker. Check this example:

You won't have heard the news, of course.
(This means that I assume you have not heard the news).

In Spanish, this idea is usually translated as "Entiendo que no estás a tanto (que no te has enterado) de las novedades".

FUTURE PERFECT SIMPLE

This verbal tense describes an event that will be finished by a particular time in the future. It also shows that something will occur before another action occurs in the future or before a specific time in the future.

The basic grammar structure is WILL ► HAVE ► PAST PARTICIPLE.

In the affirmative form, this tense can be contracted replacing WILL by 'LL. In the negative form, WILL NOT can be replaced by WON'T.

When we want to make up the interrogative, we need to change the order of words. First, we start with the auxiliary word WILL, followed by the subject and the PAST PARTICIPLE of the main verb. 

Let us see some examples:

AFFIRMATIVE: They will ('ll) have finished their test by the time the teacher arrives.

NEGATIVE: They will not (won't) have finished their test by the time the teacher arrives.

INTERROGATIVE: Will they have finished their test by the time the teacher arrives?

FUTURE PERFECT PROGRESSIVE

This verbal tense refers to a progressive event that will be completed at some point in the future. It is used to show that an event will continue up until a particular event or time in the future. It is usually used with expressions indicating duration (for five minutes, for two weeks).

The basic grammar structure is WILL ► HAVE ► BEEN ► 'ING' VERB.

In the affirmative form, this tense can be contracted replacing WILL by 'LL. In the negative form, WILL NOT can be replaced by WON'T.

When we want to make up the interrogative, we need to change the order of words. First, we start with the auxiliary word WILL, followed by the subject, BEEN and the 'ING' VERB (gerund form of the main verb). 

Check these examples in the affirmative and interrogative forms:

AFFIRMATIVE: Mr Grammar will ('ll)have been teaching for more than 50 years when he retires.

INTERROGATIVE: Will Mr Grammar have been teaching for more than 50 years when he retires?

A COMMON MISTAKE

We use the present perfect simple when we give the number of completed actions. Check this:

WRONG: My daughter Sara will have been working in three different positions at the company by the end of the year.

CORRECT: My daughter Sara will have worked in three different positions at the company by the end of this year.

On the next page you can practise this grammar.