A:维持原来匀速下滑
B:减速下滑
C:向上运动
D:可能相对地面不动.
——More and more students wear glasses in our school these days.——I agree with you. Students ___ keep on doing eye exercises to protect their eyes.
下列关于文学常识的表述,有错误的一项是( )
下列动物行为从获得途径上看,不属于学习行为的是( )