Tenses:

Jamil writes a letter                present tense

Jamil wrote a letter                 past tense

Jamil will write a letter            future tense

The Present, Past and Future are the three main tenses In English

Present Tense

I write a letter                          present Indefinite

I am writing a letter                 present Continuous

I have written a letter              present Perfect

I have been writing a letter  Present Perfect Continuous

Past Tense

I wrote a letter                          past Indefinite

I was writing a letter                 past continuous

I hid written a letter (when he came)       past perfect

I had been writing a letter    past Perfect Continuous

Future tense

I shall write a letter                 future indefinite

I shall be writing a letter         future continuous

I shall have written a letter     future perfect

I shall have been writing a letter     future Perfect Continuous

The gerund: When the verb is used as noun by adding “ing” to it.

His writing is legible

She was tired of waiting

Stop talking

Seeing is believing