栓剂油脂性基质（）.
A．蜂蜡
B．羊毛脂
C．甘油明胶
D．部分合成脂肪酸甘油酯
E．凡士林
参考答案：D
________ is often the case with human beings, many animals sleep a lot when young, but sleep much less when they get older.
A．Which
B．What
C．As
D．That
架线式电机车在瓦斯矿井中使用时，必须符合哪些规定？
