证券公司应当按照上一年营业费用总额的( )来计算营运风险的风险准备。
A.5%
B.10%
C.20%
D.25%
参考答案:B
请写出dB和dBm的定义公式。
We can't do _____ work today because it is _____ hot.[ ]
A. too many; too much
B. much too; too much
C. too much; much too
D. too much; many too