----- Is that Mr. Smith? ----- It ______ be him, because he has gone to Beijing. A. must B. should C. can’t
I'm going to take ______lessons every day.
--- I have a fever. --- _______. You’d better go to see a doctor.
Tom and Jim are talking. We should tell them _______ noise while watching birds.
---_______ do people cut down so many trees here? --- To get enough space for a new road.
--- Red-crowned cranes need more people’s help. ---Yes. People working in the reserves are doing everything they can ____these birds.