Записать формулы сокращенного умножения на языке Паскаль

Пример:

а2-в2=(а-в)(а+в)

sqr(а) - sqr(в)=(а-в)*(а+в)

Подробно пожалуйста

1.look! Somebody_____ the tree! 

 a)have already broken b)has already broken c)already broken 

2.Jane_____the competition Iast week.

a)heven't won b)didn't win c)hasn't won

3.My frend_____to China iast summer.

a)went b)has qone c)have gone

4.His brother____ his ankle two years ago.

a)have twisted b) twisted c)  has twisted

5.Can I speark to Jim,piease? Sorry,but he ____.

a) heve just ieft b) just ieft c) hasjust ieft

6.I____ Peter since last Mondau.

a)haven't seen b)didn't see c)hasn't seen

7.I_____to Washinqton DC

a)have naver been b)has never been c)never was

8.My parents_____to Russia in 1991.

a)moved b)have moved c)has moved

9.Slav_____to play the piano for 3 yers.

a)has learnt b)learnt c)have learnt

10.They ____table tennis last week.

a)played b)have played c)have play

11.She______a test.Please,check it!

a)has written b)wrote c)have written

12.He_____since 1998.

a)have never swum b)has never swum c)never swam

13.I with my friends _____in London.

A)was B)has never been C)have never been

14.I_____a new car yesterdey.

A)bought B)have bought C)has bought

15. My aunt____pictures.

A)already drew B)has already drawn C)have already drawn