导流隧洞进出口应与上下游水流相衔接，与河道主流的交角以（）左右为宜。
A.300
B.450
C.600
参考答案：A
My parents and I are flying to London for a holiday and I’ll_________ the chance to practice my spoken English.
A．come up with
B．make use of
C．get along with
D．get tired of
A．机械的效率越高，做功越多
B．机械的效率越高，做功越快
C．机械的功率越大，做功越多
D．机械的功率越大，做功越快
