The question that puzzled them is ____ they can get rid of the air pollution in the area.

A．how is it that

B．that how

C．what is it

D．how it is that

6010-300KV无刷电机相较于4010-300KV电机，其性能（）。

A.转速更高

B.功率更大

C.效率更高

D.寿命更长