由于（），使液压牛头刨床的油温过高。
A.内泄漏大
B.系统压力过高
C.工作负荷过大
D.油池油面过低
E.液压油太脏
参考答案：A, D
In order to continue to learn by ourselves when we have left school, we must ______ learn how to study in the school now.
A．in all
B．after all
C．above all
D．at all
钩端螺旋体病主要的传染源和储存宿主是（）
A.病人
B.鼠、猪
C.蚊
D.犬
E.蝇
