【单选题】People are always curious because ______.
A.
they know nothing about the world
B.
they know little about the world
C.
there are answers they do not have
【单选题】The managers discussed the plan that they would like to see the next year .
【简答题】传动系统按能量传递方式不同,划分()传动,()传动,()传动,()传动等