They (to recieve) a letter.
They recieved a letter.
They were recieving a letter.
They are recieving a letter.
They recieve a letter.
I (to do) homework.
I did homework.
I was doing homework.
I am doing homework.
I do homework.
He (to get) back his money.
He got back his money.
He was getting back his money.
He is getting back his money.
He gets back his money.