We have seen that the past perfect tense is used to talk about a completed past action. Note that when two past actions have to be mentioned, the past perfect is used for the earlier of the two, and the simple past for the later.

The patient had died before the doctor arrived.
The thief had escaped before the police came.
The train had left before we reached the station.

Sentence 4 indicates that the action of writing which started some time in the past had been continuing uninterruptedly till another later action or point of time in the past. An example would make this clear:

I had been giving him financial help till he got a good job.
We had been working in the garden until he came.

I had been reading until the lights went off.

Future tense
Just as the present and past tenses have four forms, the future tense also has four forms:

a)    Future indefinite or Simple future
b)    Future continuous
c)    Future perfect
d)    Future perfect continuous

Read the sentences given below:

1.    I will write.
2.    I will be writing.
3.    I will have written.
4.    I will have been writing.

All these sentences refer to the future time. The verb in sentence 1 is said to be in the future indefinite tense because it simply makes a statement about an action to be performed in the future without indicating any details about it.

Sentence 2 shows that the action will be continuing for a certain period of time in the future and hence the verb is said to be in the future continuous tense.

The verb in sentence 3 shows that the action will be completed or perfected by a certain point of time in the future and hence it is said to be in the future perfect tense. The future perfect tense emphasizes the completion of the action by a certain point of time in the future.

The verb in sentence 4 is said to be in the future perfect continuous tense because it indicates that the action of writing which had been in progress over a period of time will continue uninterruptedly up to a certain point of time in the future. The future perfect continuous tense emphasizes the duration and continuity of the action rather than its completion.

You will have noticed that all the tense forms given here are in the active voice. Most of these active voice tense forms have their corresponding passive forms also. We will learn about them in another chapter.