压缩机的吸入口要安装过滤器，是为了防止气体中夹带灰尘和铁屑而造成对气缸的磨损与刮伤。
参考答案：对
The scientist made several discoveries, _______. [ ]
A. which we think are important
B. which we think that is important
C. we think which are important
D. which we think is important
活血祛瘀药的共同作用是( )
A．活血通经
B．活血行气
C．活血疗伤
D．活血消痈
E．活血祛瘀
