同温同压下,等质量的CH4和SO2相比较,下列叙述正确的是:
A.密度比是:4 :1
B.体积比:4 :1
C.原子个数比:5 :3
D.分子数比:1 :4
答案:B
—Could I watch TV, Mum? I want to have a rest.
—No, you _______. You must finish your homework first.[ ]
A. mustn't
B. couldn't
C. may not
D. can't
人生价值实现的条件是什么?