Participles and the formation of perfect tenses
Participles are incomplete verb forms. In order to function as real verbs, they should be used with auxiliary verbs.
There are two kinds of participles in English: the present participle and the past participle.
The present participle always ends in -ing. Examples are: running, writing, reading, singing, dancing, waiting etc. The past participle form of most verbs end in -ed. Examples are: climbed, jumped, waited, wanted, called, studied etc. Some verbs, however, have past participles that do not end in -ed.
Some end in -en:
Written, smitten, bitten, taken etc.
Some past participles end in -t:
Meant, slept, crept etc.
There are also a few irregular verbs that have distinctive past participle forms:
Participles are used in the formation of the following tenses:
present perfect continuous
past perfect continuous
The present perfect tense forms are constructed by putting has or have before the past participle form of the verb. For example, the present perfect tense form of the verb write is has/have written. Similarly, the present perfect tense form of the verb go is has/have gone.
John has gone to the market.
They have accepted the offer.
I have invited all of my friends.
Past Perfect Tense
The past perfect tense forms are constructed by putting had before the past participle form of the verb. For example, the past perfect form of the verb write is had written.
The train had left before we reached the station.
The patient had died before the doctor arrived.
Present Perfect Progressive
The present perfect progressive tense forms are constructed by putting has/have + been before the present participle form of the verb.
We have been waiting since morning.
It has been raining since yesterday.
I have been thinking of writing a novel.
Past Perfect Progressive
The past perfect progressive tense forms are constructed by putting had been before the present participle form of the verb.
I had been giving him financial assistance until he got a good job.
When the explosion occurred, they had been playing nearby.