Jim tried his best to raise his spirits though he failed the exam.
A:cheer himself up
B:make himself calm
C:keep himself down
读图,回答下题
下列各句中,划线的成语使用正确的一项是( )
用人的胰岛素基因制成的DNA探针检测下列物质,不能形成杂交分子的是( )
化学就在我们身边.请从下列物质中选择适当的物质填空.(填字母序号)
A.CH4 B.维生素A C.生石灰 D.活性炭 E.葡萄糖 F.食盐