The past perfect tense is usually used to talk about something that had happened before something else in the past. Consider this situation: We are talking about two past events. In this case, we will use the past perfect tense for the earlier of the two actions and simple past for the other.

Of course, in some cases it is possible to express these ideas using time conjunctions like before and after. In this case, the use of the past perfect tense is optional.

Consider the example sentences given below.

• They had lived in Sydney for ten years before they moved to Toronto.

Of course, here the time conjunction before indicates which action occurred first and hence in this case the use of the past perfect tense is optional.

• They lived in Sydney for ten years before they moved to Toronto.
• She had finished dinner before guests arrived. OR She finished dinner before guests arrived.

Past Perfect Negative Form

The negative forms are made by putting not after had.

• The visitors had left before I reached home. (Affirmative)
• The visitors had not left before I reached home. (Negative)

Time conjunctions used with the past perfect tense

Already / Before

Already can be used with affirmative sentences in the past perfect tense to indicate that something had been completed before another action occurred.

Before is possible in negative and interrogative sentences as well as affirmative sentences.

To indicate duration we can use the word for.

• She had worked in television for five years before she joined the film industry.

By the Time

The expression by the time is used to indicate the moment up until which something had happened.

• They had finished lunch by the time I reached home.