Perfect Tense

The perfect tense is a kind of verb tense used to represent completed actions. It includes the past perfect tense, the present perfect tense, and the future perfect tense. It is sometimes called the complete tense.

Past Perfect Tense
To make the past perfect tense, we use the past tense of the verb "to have," that is ", had", and add it to the past participle of the main verb. For example: subject + had + past participle = past perfect tense.

For example; She had met him before dinner.


Present Perfect Tense
The present perfect tense applies to an act or event that either happened at an unspecified time in the past (e.g., we have discussed earlier) or raised in the past and remained to the present time (e.g., he has become anxious over the last hour). This tense is made by have/has + the past participle.

Future Perfect Tense
The Future Perfect tense is a simple tense to learn and apply. The Future Perfect tells about the past in the future.

Examples; 

• She will have prepared lunch.

• He will have reached.

"Since" or "For"

We often use For and Since when speaking about time.

for + period: a "period" is a span of time - ten minutes, three weeks, two years. For means "from the start of the period to the end of the period".

For example;

• They study for three hours every day.
• He has been living in London for five months.

since + point: a "point" is a specific time - 8 o'clock, 7th January, Sunday. Since means "from a period in the past until now".

For example;

• He has been here since 11am.
• He has been working since he arrived.