Hello, Beligma! Thank you for your homework.

MY corrections:

0.If I buy, I (will be) am glad. 

1.If I bUY it, I wILL be happy

2.If I bouGHT it, then I WOULD be glad. 

3.If I HAD bought IT, I would HAVE BEEN glad. 

Task 2.

1.He bUYS bookS in a store. 

The bookS ARE read aT home. 

2.He IS BUYING a book in a store. 

The book is BEING BOUGHT at home. 

3.He has read the book at home. 

The book HAS BEEN read at home. 

Task 3.

1.I buy bananas for break fast. 

A friend said she bought bananas for breakfast. 

2.I HAVE bOUGHT bananas for breakfast FOR THREE dayS. 

My friend said that she HAD BOUGHT bananas for breakfast for three days. 

3.Yesterday I bought bananas. 

A friend said she HAD bought bananas the day before. 

4.I'v bought bananas for there weeks now. 

(A friend said had been tools, a friend said she there weeks)???. 

5.I have never bought tools. A friend said she had never bought tools. 

Your grade is 4.