A:are operating
B:were operating
C:operate
D:operated
隋朝时期,一批牡丹花从洛阳沿运河到余杭,依次需要经过( )
关于下图所示各装置的叙述中,正确的是 ( )
Bill doesn't like the sunglasses in the ad because they can't __________ the sun well.