每个排烟系统设有排烟口的数量不宜超过( )个，以减少漏风量对排烟效果的影响。
A．10
B．20
C．25
D．30
参考答案：D
物体以8m/s的速度开始做匀减速直线运动，运动16m后停下，则（ ）
A．物体运动的加速度大小为2m/s2
B．物体运动的加速度大小为4m/s2
C．物体运动的时间为2s
D．物体运动的时间为4s
—Why didn't you buy the gold ring?
— I ______, but I didn't have the money.[ ]
A. would have
B. bought
C. would like to
D. had bought
had bought