一、 单项选择：从各小题所给的A、B、C、D四个选项中，选出一个最佳答案。（共20小题；每小题1分，满分20分。）
1．You can’t pass the exam _____C____ you study hard.
A．if B．because C．unless D．so
2．Look out! Don’t get too close to the house roof is under repair.A
A．whose B．which C．of which D．that
3．If it were not for the fact that she ____C_____ sing, l would invite her to the party.
A．couldn’t B．shouldn’t C．can’t D．might not
4．Always read the ___B______ on the bottle carefully and take the right amount of medicine.
A．explanations B．instructions
C．descriptions D．introductions
5．Green products are becoming more and more popular because they are environmentally .
A．common B．various C．friendly D．changeable
6．—What happened to you this morning?
—The teacher asked me for my _____ when I was late again.
A．meaning B．idea C．excuse D．answer
7．—Would you help me put away these things?
—_________.
A．Yes, quite right B．Never mind
C．You’re welcome D．With pleasure
8．—Here’s coffee and tea. You many have ________.
—Thanks.
A．either B．each C．one D．it
9．—Will you please stay here for the party?
—Sorry, I ________. I’ll have to go to an important meeting.
A．mustn’t B．needn’t C．can’t D．won’t
10．—What does the lady look like?
—_________.
A．She’s fine and well B．She’s really a nice lady
C．She’s tall and thin D．She like wearing skirts