The girl in the classroom ______ be Sarah. She has gone to the library.
A. may B. must C. can’t D. needn’t
We have worked so long. Shall we stop ______ a rest?
A. have B. to having C. having D. to have
Rules are helpful to us, ______ we have to follow them.
A. so B. but C. or D. because
Tim is going to give his father a surprise ______ Father’s Day.
A. in B. at C. on D. by
Ladies and gentlemen, attention please! I have ______ important to tell you.
A. nothing B. something
C. everything D. anything
I like hiking in the forest because the air is pretty ______.
A. free B. dirty C. polluted D. fresh
