材料的硬度属于（）。
A.物理性能
B.化学性能
C.工业性能
D.机械性能
参考答案：D
桂枝茯苓丸的治法是（）。
In order to help the police, the eyewitness described what he had seen very carefully not to______ any key clues.
A．cut off
B．leave off
C．squeeze out
D．leave out
