17. PERFECT TENSE

• Present Perfect Tense is used for describing a past action's effect an the present.

- Pattern I : S + have/has + been + Complement
- Pattern II : S + have/has + V3 + O/Adv

• Past Perfect Tense is a kind of tense is used to describe an action or an event that start in a certain time in the post and completed or finished fill certain time in tehe 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.

- Pattern : S + had + V3 + Complement

• Present Future Perfect Tense is used to assert an action or an event that will happened or will finished at the definite time in the future.

- Pattern I : S (except I) + will/shall + have + been + Complement
- Pattern II : S + will/shall + have + V3 + O/Adv

• Past Future Perfect Tense is used to assert an action or an event that will happened before or at the other event happened at the past future.

- Pattern I : S + would/should + have + been + Complement
- Pattern II : S + would/should + have +V3 + Complement