车辆减速器制动时对车辆入口速度有何要求？
参考答案：
减速器制动时，车辆入口速度应不大于7m/s.
He didn't come to the meeting yesterday.That was _____ he had to see his sister off at the airport. [ ]
A. that
B. why
C. because
D. how
设表达式E=a*(b-c)/(d+e)+f*(g+h)，则E的逆波兰表达式为 (40) ，E的波兰表达式为 (41) 。
（41）处填（）。
A．a*b-c/d-e+f*g+h
B．abc-*de+/fgh+*+
C．+/*a-bc+de*f+gh
D．abc-*de+/f8h++*
