Mom，could I watch the game show now？
Sorry，you can't watch it ________ you clean your room．（ ）
| A． |
when |
B． |
if |
C． |
after |
D． |
until |
When going up stairs or down stairs，we need to walk on the right，leaving the left space for the people who ___．（ ）
| A． |
hurry up |
| B． |
look around |
| C． |
run away |
No matter what problems we meet，we should try to solve them，and even though we fail，teachers and parents___ us．（ ）
| A． |
are strict with |
| B． |
are worried about |
| C． |
are proud of |
When you're invited to have dinner at home by an American friend，you should be ___ or a little later．It's different from our Chinese custom．（ ）
| A． |
on time |
| B． |
on business |
| C． |
on show |
If your best friend tells you his secret，it's ___ for you to keep them for him．By doing this，you can win others'trust．（ ）
| A． |
special |
B． |
necessary |
C． |
possible |
Our teachers have been with us for nearly three years ___ we came to junior high school．We should t
hank them for what they have done for us．（ ）
| A． |
until |
B． |
before |
C． |
since |