— Mary, how did your Math test go?
— I had thought I ________, but in fact I came in the top 10 in my class.
A:should have failed
B:couldn't have failed
C:might have failed
D:shouldn't have failed
如图是由四个相同的小正方体组成的立体图形,它的左视图为( )
2009年“世界环境日”提出“团结起来应对气候变化”。下列做法不能减轻温室效应的是( )
在等比数列{an}中,Sn=k·(12)n,则实数k的值为( )
对于孤立体系中发生的实际过程,下列说法中正确的是( )
化学与人类生活、生产和社会可持续发展密切相关,下列说法正确的是( )