The past perfect tense
Form: Subject + had + past participle form of the verb
- He had worked.
- She had played.
- They had gone.
- We had waited.
The past perfect tense denotes an action completed at some point in the past before some other action commenced. Note that when we have to refer to two actions in the past, the past perfect is used for the earlier action, and the simple past for the later one.
- The patient had died before the doctor arrived.
- The train had left before we reached the station.
The past perfect continuous tense
Form: Subject + had + been + ing form of the verb
- He had been writing.
- I had been reading.
- They had been working.
The past perfect continuous tense is used to talk about an action which started some time in the past and continued till a later point of time in the past when some other action commenced.
- The war had been going on for two years when John enlisted.
- I had been giving him financial assistance till he got a job.
In sentence 1, the war started some time in the past, continued for two years and was still continuing when John enlisted.