手动弯管机，一般弯制管径不超过______mm的管子。
A．25
B．32
C．40
D．50
参考答案：B
— Who is the man over there? Is it Mr. Li?
— No, it _____ be him. Mr. Li is much taller. [ ]
A. mustn't
B. may not
C. can't
D. needn't
由于受热不均而形成的气压带有（）
①赤道低气压带
②副热带高气压带
③副极地低气压带
④极地高气压带
A.①②
B.②④
C.①④
D.①③
