A:received, accept
B:received, accepted
C:accepted, receive
D:accepted, accept
观察下列等式: 11×2=1−12 , 12×3=12−13 , 13×4=13−14 ,
将以上三个等式两边分别相加得:
11×2+12×3+13×4=1−12+12−13+13−14=1−14=34 .
填上合适的介词。
The sound ____ the wind .
如图所示,若入射光线与平面镜成30°夹角,则( )