FUNCTIONS OF THE PAST PERFECT
The past perfect refers to a time earlier than before now. It is used to make it clear that one event happened before another in the past. It does not matter which event is mentioned first - the tense makes it clear which one happened first.
In these examples, Event A is the event that happened first and Event B is the second or more recent event:
| Event A | Event B |
| John had gone out | when I arrived in the office. |
| Event A | Event B |
| I had saved my document | before the computer crashed. |
| Event B | Event A |
| When they arrived | we had already started cooking. |
| Event B | Event A |
| He was very tired | because he hadn't slept well. |
FORMING THE PAST PERFECT
The Past Perfect tense in English is composed of two parts: the past tense of the verb to have (had) + the past participle of the main verb.
| Subject | had | past participle |
|---|---|---|
| Affirmative | ||
| She | had | given |
| Negative | ||
| She | hadn't | asked. |
| Interrogative | ||
| Had | they | arrived? |
| Interrogative Negative | ||
| Hadn't | you | finished? |
TO DECIDE, PAST PERFECT
| Affirmative | Negative | Interrogative |
|---|---|---|
| I had decided | I hadn't decided | Had I decided? |
| You had decided | You hadn't decided | Had you decided? |
| She had decided | She hadn't decided | Had she decided? |
| We had decided | We hadn't decided | Had we decided? |
| They had decided | They hadn't decided | Had they decided? |
PAST PERFECT + JUST
'Just' is used with the past perfect to refer to an event that was only a short time earlier than before now, e.g.
- The train had just left when I arrived at the station.
- She had just left the room when the police arrived.
- I had just put the washing out when it started to rain.
sumber:http://www.ef.com/english-resources/english-grammar/past-perfect-tense/
