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GRAMMAR EXTRA: We use the present perfect tense with the following structures: It/this/that is the first/thesecond/the best/the only/the worst ...
It’s the first time I’ve ever had to write such a long assignment.
That’s the sixth cup of coffee you’ve had today.
Unit 4. Past tenses II. Past Perfect

+	Had + past participle	He’d started the assignment.
--	Had not + past participle	I hadn’t started the assignment
?	Had … + past participle?	Had you started the assignment?

We use the past perfect:

• 
  when we are talking about the past and want to mention something that happened earlier:
  

His father was a composer and his grandfather had also been a musician. (Mozart's grandfather was a musician and then later his father became a composer) Sometimes we use words like just or already. Notice that these adverbs go between the auxiliary and the main verb:
By the time he was 17, Mozart's reputation had already begun to spread through Europe.
!!! We use the past simple if the events are mentioned in chronological order:
Mozart’s grandfather was a musician and his father was a composer.

• 
  for an action which happened before another past action or before a stated time in the past. Ann had finished her homework by five o'clock.
  
• 
  for an action which finished in the past and whose result was visible at a later point in the past. She had sprained her ankle a few days earlier and it was still hurting.
  
• 
  for a general situation in the past. Everything had seemed normal at first.
  
• 
  with words like when, as soon as, by the time, after to show the order of events:
  

When Mozart was born, five of his siblings had already died. (Mozart's siblings died first, then Mozart was born)
!!! Notice the difference in meaning between these two sentences:
When I got home, my husband cooked dinner. (= I got home and then my husband cooked dinner)
When I got home, my husband had cooked dinner. (= my husband cooked dinner before I got home)

• 
  to talk about an indefinite time before a particular point in the past, often with words like always, sometimes, never, before, by + fixed time:
  

His family were richer than they had ever been before. (= they were not as rich at any time before this point in the past)
By the time he was six, the little boy had written a composition of his own,

• 
  to report past events using reporting verbs: The man told me he had met my father a long time before.
  

The time expressions we use with the past perfect are: before, after, already, justf for, since, till/until, when, by the time, never, etc
Past Perfect Continuous

+	had been + verb + ing	He’d been studying for ages.
--	had not been + verb + ing	He hadn’t been studying for long.
?	had …. been + verb + ing?	Had they been studying for long?

We use the past perfect continuous:

• 
  to put emphasis on the duration of an action which started and finished in the past, before another action or stated time in the past, usually with for or since. He had been driving for an hour when he realised he had forgotten to lock the door.
  
• 
  for an action which lasted for some time in the past and whose result was visible in the past. He had been swimming and his hair was still wet.