--- Do you know Amy came to school this morning?
--- Her bike was broken, so she had to walk.
下列关于O2的说法中,正确的是( )
I took about two hours (小时) my homework.
皮筏漂流是近几年来一项热门的水上活动,一漂流者坐在橡皮筏上顺流而下,下列说法正确的是( )