速度大于200km/h的接触网，弓网接触力应“（）”，不超过“（）”。
参考答案：大于0；350N
The Russian rocket designer has died. For many years, he ______ as an important assistant to the father of Soviet space program.
A．serves
B．was serving
C．served
D．has served
何谓终极噪声?
