叉车上常用的是（）或单作用活塞式起升油缸。
参考答案：单作用柱塞式起升油缸
With so much work ______ , I have to stay at home for a whole day and I’m almost at breaking point.
A．done
B．doing
C．to do
D．having done
人工种子的制作流程
