通信用风力发电机组的安全风速要求不小于(),超过此风速,发电机组应能自行保护不被吹毁。
A.20m/s
B.50m/s
C.80m/s
D.100m/s
参考答案:B
Iraq has ______ too many wars since 1990, making his people _______ a lot.
A.got through; pay
B.looked through; face
C.gone through; suffer
D.passed through; destroy
在下列传染病中罕见有病原携带者的是()
A.流感
B.麻疹
C.伤寒
D.痢疾
E.白喉