A:always; seldom
B:seldom; often
C:sometimes; always
D:never; seldom
蚕丝被是以天然蚕丝为原料制作的丝绸制品,具有优良的保暖、透气、吸湿、柔软等特性.那么蚕吐丝在什么时期( )
如图是地球公转及其轨道示意图,下列说法正确的是( )
On the past, there was a cute girl.
____改为____
She tried to finish all the work in one day but finally _____ and had to take a rest.