—Whose shorts are these? —They are ______.
A:my
B:I
C:mine
—How long have you _________ your watch? It looks new.
—Only about three weeks.
图为肺泡内的气体交换示意图,下列叙述正确的是( )
下列物质中既是光合作用的原料,又是呼吸作用的产物的一组是( )
I usually go to school by bike, today I took a bus because it rained heavily.