--Who has opened the door? ---I think it be Lin Tao. He’s always the first to get here.A.

问题补充：

--Who has opened the door? ---I think it be Lin Tao. He’s always the first to get here.

A. is able to

B. can

C. must

D. mustn’t

答案：

A. is able to

B. can

(答案→)C. must

D. mustn’t

解析：这是肯定的推测, 所以只能选用must