Perfect Tense

Present perfect tense is used to describing a past action’s effect on the present :

He has arrived, Now he is here.

This holds true for events that have just been secluded as well as for events that have not yet occurred.

Present perfect is formed by combining have/has with the main verb’s past participle form :

- I have arrived

- I have not arrived

- Has she arrived ?

Past perfect tense is a kind of tense that is used to describe an action or an event that started in a certain time in the past and completed or finished till certain time in the past too ; or past perfect tense is used to express an action or an event that had happened before the other event or action happened.

The pattern :

(+)S+had+VIII+complement

(-)S+had not+VIII+complement

(?)Had+S+VIII+complement

Example :

(+)We had eaten before they come

(-)We had not eaten before they come

(?)Had they eaten before we come ?

Adverbs used :

From 1998 to 1999, once, twice, etc