轻度精神发育迟滞时，智商为
A．30～49B．50～70C．20～34D．＜220E．75～89
参考答案：B
对于函数y=2x-1，当自变量增加m时，相应的函数值增加[ ]
A．2m
B．2m-1
C．m
D．2m+1
The winds you would expect to encounter in the North Atlantic between latitudes 5° and 30° are known as the（）.
A.Doldrums
B.Westerlies
C.Trades
D.Easterlies
