I.1) If you are busy, I’ll leave you alone.
2) were / ‘d
leave
3) had been
/ ‘d have left
II. 1) If Mother
buys a cake, we’ll have a very nice tea party
2) bought /
‘d have
3) had
bought / we’d have had
III. 1)If
we receive a telegram from him, we won’t worry.
2) received
/ wouldn’t worry
3) had
received / wouldn’t have worried
IV. 1) If
you don’t work hard, you’ll fail the exam.
2) didn’t
work / ‘d fail
3) hadn’t
worked / ‘d have failed