Feathers fall to the ground slowly, ________ stones fall much faster.
A:but
B:however
C:while
D:yet
关于我国民族叙述正确的是( )
盆栽的绿萝,窗台外侧比窗台内侧的长势茂盛,这一现象说明生物( )
下列关系中,互相垂直的两条直线是( )