The perfect tenses

Form: have + past participle
Meaning: The perfect tenses all give the idea that one thing happens before another time or event.

PRESENT PERFECT

(a) I have already eaten.

I finished eating sometime before now. The exact time is not important.

PAST PERFECT

(b) I had already eaten when they arrived.

First I finished eating . Later they arrived. My eating was completely finished before another time in the past.

FUTURE PERFECT

(c) I will already have eaten when they arrive.

First I will finish eating. Later they will arrive. My eating will be completely finished before another time in the future.



Cheers!
Naeem