单项选择题
（）the moveable plate and floating ring inside the pump is very difficult.
A.Having adjusted
B.Being adjusted
C.To adjust
D.Adjusted
点击查看答案&解析
相关考题
-
单项选择题
The four-stroke cycle begins with the piston （）.
A.coming up from the BDC
B.coming up from the TDC
C.coming down from the BDC
D.coming down from the TDC -
单项选择题
Pump up the starting air reservoirs to their maximum pressure and （）the air reservoirs and air system.
A.open
B.close
C.drain
D.vent -
单项选择题
James Watt （）the steam engine in 1796.
A.discovered
B.had discovered
C.invented
D.had invented
