. It is usually warm in my hometown in March but it be rather cold sometimes. A. mustB.

问题补充：

. It is usually warm in my hometown in March, but it be rather cold sometimes.

A. must

B. can

C. should

D. would

答案：

A. must

(答案→)B. can

C. should

D. would

解析：can表示推测时通常只用于否定句或疑问句，很少用于肯定句。但有两种情况是例外（即可用于肯定句）：一是表示纯理论上的可能性，二是表示“有时”，如：Even experienced teachers can make mistakes. 即使是有经验的教师也可能出错。She can be very unpleasant. 她有时很令人讨厌。