Task 3.
Was;
Were;
Was;
Was;
Were.
Task 4.
Wasn't;
Didn't;
Weren't;
Didn't.
Task 5
Did;
Did;
Where;
Was.
Task 6.
Did you write a test two days ago?
Yesterday, i didn't get up at 8 a.m.
We were in the country last summer.
When did you swim in the river?
Hwo saw this film?
I sent a letter last month
Task 7
Неуспеваю дальше доделать, извини.