TD中心机房地网到机房的接地引入线的长度不宜超过()。
A.10m
B.30m
C.20m
D.40m
参考答案:B
I bought a new sweater last weekend. It _______ me 120 yuan. [ ]
A. paid
B. take
C. cost
D. spent
常见钢按用途分类?