煤与瓦斯突出在时间上和空间上有一定的集中性和突然性，它是一种伴有声响和猛烈力能效应的动力现象。
参考答案：对
Between 1897 and 1919 at least 29 motion pictures in which artificial beings were portrayed ______ .
A．had produced
B．have been produced
C．would have produced
D．had been produced
香砂养胃丸的功能是（）
A．温中和胃
B．益气健脾，和胃
C．开胃消食，行气泻水
D．健脾开胃，行气消痞
E．消积开胃，活血止痛
