20, Because she was sick, she stayed in bed
21, If you had worked hard, you wouldn't have got bad marks
22, -The shirt is so tight that they boy can't wear it
-The shirt is too tight for the boy to wear
23, -does Peter
-enjoys scientific too
24, Mike drives more carefully than his brother
25, If she hadn't worked hard, she wouldn't have got wages
26, If you don't phone me tonight, you won't get any information
27, Tom used to cry a lot when he was a child
28, -This problem is too difficult fo him to solve
-It is such a difficult problem that he can't solve it
-This problem is so difficult that he can't solve it
