Why did you just sit and watch？ You _______ me.
| A．could help | B．should help |
| C．could have helped | D．must have helped |
29. New ways _____ to prevent the river _____.
| A．have found out, from polluting |
| B．have found, from being polluted |
| C．have been found out, from being polluted |
| D．have been found, from being polluted |
28. The first thing she did _____ up to her trainer and thanked her.
| A．was go | B．was going | C．and went | D．Go |
27. The boy gathered all his _____ to stand up.
| A．strength | B．power | C．force | D．Energy |
26. We were all waiting for you. You _____ for the seaside by yourself without
leaving a message.
| A．mustn’t leave | B．shouldn’t have left | C．could not have left | D．needn’t leave |
25. When a person wants to operate the computer, _____ read instructions first.
| A．you will have to | B．one must | C．they will have to | D．he has to |