RRU电源线屏蔽层接地,若电缆长度超过()米,需在电缆中间部分加做一处防雷接地。
A.80
B.70
C.60
D.50
参考答案:B
已知f(x)=x2-2x,g(x)=mx+2,对∀x1∈[-1,2],∃x0∈[-1,2],使g(x1)=f(x0),则m的取值范围是______.
----In recent years, _____problem of global warming has become very serious.
----That’s right. People are facing _____diversity of natural disasters now.
A./, a
B.a, the
C.the, a
D.a, a