We still have some other ways to solve the problem．You ______ be worried．
| A．mustn’t | B．can’t |
| C．don’t have to | D．may not |
Harry Potter has made reading popular again, ______ is why parents and teachers like the book, too．
| A．that | B．who |
| C．which | D．what |
Some countries have banned smoking in public places ______ public health．
| A．improve | B．to improve |
| C．improving | D．improved |
Mr．Smith had to go to work by bus this morning as his car ______．
| A．would repair | B．was repairing |
| C．had been repaired | D．was being repaired |
Food and fruit are forbidden in the library, ______ you are allowed to have drinks and sweets with you．
| A．and | B．but | C．so | D．or |