甲数除以乙数的商是0.4，甲数与乙数的最简整数比是______．
甲数÷乙数=甲数：乙数，
=0.4，
=25，
=2：5；故答案为：2：5．
The class teacher came up and put a jacket _____ the boy to prevent him from catching a cold .
A．by
B．with
C．off
D．over
采集试样的工具应干燥、纯净，样品的数量根据分析的化学元素多少而定。一般常规分析试样取（）g。
A.30-40
B.50-60
C.70-80
D.80-100
