It is usually cool in April in Chongqing but it sometimes be rather hot for a few days.

问题补充：

It is usually cool in April in Chongqing, but it sometimes be rather hot for a few days.

A. can

B. must

C. shall

D. ought to

答案：

(答案→)A. can

B. must

C. shall

D. ought to

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