-- Look at that girl. Is it Susan?

--No, it _______ be her. She has gone back to her home town .

A．can't

B．mustn't

C．needn't

D．may not.

身体练习中（）要素，表现出时间、空间、动力学的特征

A、练习轨迹

B、练习力量

C、练习节奏

D、练习速率