通讯基站对接地电阻的阻值要求愈小愈好,不能超过规定值。在国标中,对于移动基站来说接地电阻应不大于()。
A、6Ω
B、10Ω
C、3Ω
D、5Ω
参考答案:D
-Are there any English Story books for us students in the library?
-There are only a few, _____.
A.if any
B.if there
C.if some
D.if has
已知大麦籽粒有壳(N)对无壳(n),有芒(H)对无芒(h)为完全显性。现以有芒、有壳大麦×无芒、无壳大麦,所得子代有1/2为有芒有壳,1/2为无芒有壳,则亲本有芒有壳的基因型必为()
A.NnHh
B.NnHH
C.NNHh
D.NNHH