When the completion of the action is emphasized the Past Perfect is used.

He knew the poem by heart when he had heard it several times.

I noticed that somebody was sitting at the table only when I had already entered

the room.

◆ Notice the use of the Past Perfect and the Past indefinite in the following examples:

a) he had closed the window and was sitting in his armchair reading a newspaper.

b) He closed the window, sat down in the armchair and began reading his newspaper.

a) The rain had stopped and the sun was shining brightly.

b) The rain stopped and the sun came out again.

a) He had turned on the light and was sitting at his desk writing letters.

b) He turned on the light, sat down at his desk and began writing letters.

7. The Past Perfect is used to denote the action which began before a definite moment in the past, continued up to that moment and was still going on at that moment. The starting point or the whole period of duration of the action is indicated. To indicate the starting point the preposition since is used, to indicate the whole period of duration for is used.

a) with verbs not admitting of the Continuous form:

Examination convinced him that the deacon was dead – had been dead for some time.

b) in negative sentences:

Those two had not spoken to each other for three days and were in a state of rage.

c) with non-terminative verbs such as to work, to live, to study, to teach, to travel, to last, etc.:

The ride had lasted about ten minutes, when the truck suddenly swerved to a halt.

THE PAST PERFECT CONTINUOUS TENSE

I. The formation of the Perfect Continuous Tense

The Past Perfect Continuous is formed by means of the Past Perfect of the auxiliary verb to be and Participle I of the notional verb.

In the interrogative form the first auxiliary verb is placed before the subject.

In the negative form the negative particle not is placed after the auxiliary verb.

II. The contracted affirmative forms are:

I’d been working

We’d been working

The contracted negative forms are:

I hadn’t been working

We hadn’t been working

The negative-interrogative forms are:

Had he not been working?

Hadn’t he been working?

Had you not been working?

Hadn’t you been working?