螺杆泵较多的应用于精密机床液压系统中。
参考答案：对
Many students listened to the lecture, but I wondered how much work they took________. [ ]
A. out
B. up
C. off
D. in
润滑脂是由基础油、稳定剂、添加剂和（）。
A.皂基稠化剂制成
B.胶质制成
C.固化剂制成
