A.CaO中的离子键比MgO的弱
B.甲醇的沸点比甲醛的沸点高
C.HF、H2O的沸点比HCl、H2S的沸点高很多
D.的沸点比的沸点高
答案:D
She is good at ______ and she can dance well. [ ]
A. dances
B. dance
C. dancing
D. danced
简述佩戴安全帽的要求。