从下面各题所给的A、B、C、D四个选项中，选择可以填入空白处的最佳选项。
1. My sister is only six, but ________ can already help with some housework.
2. We have history class ________ three o’clock every Friday afternoon.
3. —_________ I take photos here?
—Sorry, you can’t. It’s not allowed in the museum.
A、 Must
B、 Need
C、 Can
D、 Will
4. After taking tennis classes, Tim is much ________ than last year.
A、 strong
B、 stronger
C、 strongest
D、 the strongest
5. —_________ will Liu Yang stay in the space station this time?
—For six months.
A、 How long
B、 How often
C、 How much
D、 How soon
6. Mr. Smith has helped me a lot, _________ I’m thankful to him.
7. The workers _________ the community center now.
A、 cleaned
B、 were cleaning
C、 will clean
D、 are cleaning
8. Don’t lose heart. If you keep working hard, you _________ some day.
A、 will succeed
B、 succeed
C、 succeeded
D、 have succeeded
9. I ________ about my sister when my phone rang. It was her!
A、 think
B、 will think
C、 was thinking
D、 am thinking
10. Jim _________ a lot about Chinese culture since he began to study in our school.
A、 learns
B、 learned
C、 will learn
D、 has learned
