Past perfect and future perfect

Past perfect tense

The past perfect tense shows an action or condition in the past that came before another action or condition in the past.

• The PAST PERFECT TENSE indicates that an action was completed (finished or “perfected”) at some point in the past before something else happened.
• The Past Perfect describes an action completed before a certain moment in the past.For example:
• I met him in New Delhi in 1996. The last I had seen him was five years before. 

• If two actions happened in the past, it may be necessary to show which action happened earlier than the other. The Past Perfect is mainly used in such situations. The Simple Past is used in one clause and the Past Perfect in the other, for example:
• I had done my exercise when Han came to see me.

• Here, the first clause is “when Han came to see me” (Simple Past Tense) and the second clause is “I had done my exercise” (Past Perfect Tense).  

Example:

• When I reached the station the train had started so I could not get into the train.

• I had written the letter before he arrived.

Future Perfect Tense

The future perfect tense shows an action or condition in the future that will occur before another action or condition in the future.

The Future Perfect Tense is used to talk about actions that will be completed by/at a certain future time.

• I shall have written my exercise by then.

• He will have left before you go to see him. 

• By the end of this month, I will have worked here for five years.