A:①是溴乙烷,②是环己烷,③是酒精
B:①是甘油,②是溴苯,③是汽油
C:①是苯,②是CCl4,③是酒精
D:①是甲苯,②是乙酸,③是苯酚
—I think students should have mobile phones to call their parents.
—________. They often use them to play games instead.
下列有关美国独立战争和南北战争的说法,不正确的是( )
假设在一个由森林、草原、鹿、狼组成的相对封闭的自然环境中,把狼杀绝,则鹿的个体数将会( )