能全面评价发动机各工况的特性称为：（）
A、外特性
B、速度特性
C、负荷性性
D、万有特性
参考答案：D
Who do you think we should have______to Shanghai to visit the 2010 World Expo?
A．to go
B．gone
C．going
D．go
Don't set him to talking philosophy or he'll go on all evening.
A．off
B．on
C．at
D．of
