It's very cold. It is_______.[ ]
A. spring
B. winter
答案:B
—Look!How long________like this?
—Three weeks! It's usual here that rain________without
stopping these days of the year.
A.has it rained;pours
B.has it been raining;pours
C.is it raining;is pouring
D.does train;pours
测量声功率和电功率的单位是()。