A:氢键是化学键
B:甲烷可与水形成氢键
C:乙醇分子跟水分子之间存在着氢键
D:碘化氢的沸点比氯化氢的沸点高是由于碘化氢分子之间存在氢键
中国人口分布不均,东部多西部少,大致有一条东北一西南走向的分界线是( )
The baby stops _______ as soon as he ______ his mother coming into the room.