新都区蜀都卫生院:riddle:why do birds fly south for winter

来源:百度文库 编辑:高校问答 时间:2024/04/29 22:56:39

Because it's too slow to walk there.

???
我小学毕业你说的什么我NO指导

the reason ?south is warmer than north in winter.cofcouse ,it's in china