- 搜標(biāo)題
- 搜題干
- 搜選項(xiàng)
單項(xiàng)選擇題
The energy for pushing this piston up can be supplied from （）, so that the piston can keep moving up and down.
A.the same piston
B.the piston nearby
C.the other pistons
D.the generators on board
