一名射击爱好者7次射击的中靶环数如下(单位:环):7,10,9,8,7,9,9,这7个数据的中位数是( )
A:7环
B:8环
C:9环
D:10环
生物以各种方式适应环境,同时,也____和____着环境.
如图植物细胞结构模式图,请据图回答.
Tom didn't go hiking with his classmates ____ his illness.