一定量炸药爆炸时放出的热量叫做炸药的（）
A.爆热
B.爆温
C.爆容
D.氧平衡
参考答案：A
—Why is the classroom so dirty?
—Sorry , sir. It ____ yesterday. We forgot to do it.[ ]
A. doesn't clean
B. didn't clean
C. isn't cleaned
D. wasn't cleaned
在探究凸透镜成像规律实验中，当烛焰位于距离凸透镜一倍焦距内时，人眼观察到烛焰成像的情形是图中的（ ）
A．
B．
C．
D．
