Past Perfect Tense:
Past Perfect is mainly used in such situations, when two actions happened in the past and it may be necessary to show which action happened earlier than
the other. The Simple Past is used in one clause and the Past Perfect in the other.
When I reached the station the train had started.
I had done my home work when Hari came to see me.
I had written the letter before he reached.
Past Continuous is used to denote an action going on at some time in the past.
The light went out while I was watching the TV.
We were listening to the FM all night.
It was getting colder.
When I saw him, he was playing piano.
Simple Past Tense:
Simple Past is used to indicate an action completed in the past.
The sheep arrived yesterday.
I received my salary a week ago.
She left the college last month.
The Simple Past is also used for past habits:
He studied many hours everyday.
She always wore an scarf.
Present Perfect Continuous Tense
Present Perfect Continuous is used for an action which began at some time in the past and is still going on;
They have been building the bridge for several months.
He has been sleeping for five hours (and still sleeping).
They have been playing since 3 o’clock.
Present Perfect Tense:
Present Perfect is used to:
-Indicate completed activities. – He has just left the office.
-express past actions whose time is not given and is indefinite. – I have never known him to be angry.
-describe past events when we think of their effect rather the action. I have cut my finger (and now it bleeding).
-denote an action beginning at some time in the past and continuing up to the present (We have lived here for eight months).