Where your brother usually lunch?
A:do; have
B:are; having
C:does; have
D:is; having
图4是某条河流的剖面图,一般面对河流下游,左手方视为左岸,右手方视为右岸。据此判断该河流位于( )
下列有关生物变异的描述中,错误的是( )