James Cameron’s movie Avatar, set in 2154,         place on a planet called Pandora.

A．will take

B．will be taken

C．takes

D．is taken

超声辐射剂量与下列哪项无关()

A．受辐射时间长短

B．声束发射功率大小

C．发射声束的频率高低

D．声束在组织中的传播速度大小

E．超声束横截面积大小