Question

he will write a letter
change voice​

Answer 1

$\huge{\mathfrak{\underline{\underline{Answer :}}}}$

A letter will be written by him.

What's the need of changing a sentence from active voice to passive voice ?

Passive voice is used to stress the thing done by doer than the doer.

The change of tenses when a sentence is changed from active voice to passive voice :

1. Simple present

Active : Make

Passive : are / am / is made

2. Present continuous

Active : is / am / are baking

Passive : is / am / are being baked

3. Past simple

Active : Write

Passive : Was / were written

4. Past continuous

Active : was / were watching

Passive : was / were being watched

5. Present Perfect

Active : have / has cleaned

Passive : have / has been cleaned

6. Past Perfect

Active : had read

Passive : had been read

7. Future simple

Active : will write

Passive : will be written

Some more things to remember while changing a sentence from active to passive one :

I → me

We → us

You → You

He → Him

She → Her

It → It

They → Them

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Answer 2

A letter is being written by him.