You will fall behind others_______ you work hard.
| A．if | B．unless |
| C．though | D．since |
About __________ of my classmates in my class were born in 2000.
A. two third B. four fifth C. three fourths
All of us find __________ difficult to do the exercise.
A. this B. it C. that
I don’t think he can read the new words so well, __________?
A. can he B. can’t he C. do you
—Must I come before 7:00 tomorrow?
—No, you ________.
A. needn’t B. mustn’t C. couldn’t
Our teacher often uses the Internet ________ he often sends emails.
A. or B. and C. but