气象上的风向是指（）.
A.风的去向
B.风的来向
C.气压梯度力的方向
参考答案：B
It's quite warm here; we ________ turn the heating on yet . [ ]
A. couldn't
B. mustn't
C. needn't
D. wouldn't
我国军费2009年居于世界第二位。
