泥浆泵排出空气包是利用（）来降低排出管内的压力波动。
A、气体的流动性
B、气体的低粘性
C、气体的可压缩性
D、气体的低密度
参考答案：C
为病人测血压时应( )。
A．洗手 B．戴手套 C．戴口罩、护目镜 D．穿隔离衣 E．戴口罩
______ he referred to in his article was often discussed by many people.
A．That
B．What
C．Whether
D．Where
