JIM型计量泵膜片破裂,将导致泵()。
A、排出压力不稳
B、排液量不足
C、完全不排液
D、运行中有异常声音
参考答案:C
Scientists ____ thousands of chemicals before they decided on the right one in the end.
A.tried out
B.found out
C.worked out
D.turned out
在野外求生时凸出的大岩石下边可以作为天然的避难所。