In winter ,some birds fly to the south 为什么要用fly啊.

In winter ,some birds fly to the south 为什么要用fly啊. In winter ,some birds_____the south.A.fly to.B In autum,some birds fly to the south.这句话的状语是? ___ winter ,some birds fly to the south___china Swallows fly to the south before winter ( ) Why do birds fly south for winter Some birds ( )to the south before winter Swallows fly to the south before winter comes .中文,为什么用comes而 Birds fly to the south ()autumn.(填介词） When winter comes,some girds will fly to the south,__will st 谁能用英语回答这个脑筋急转弯的问题呢why do birds fly south in the winter why do brids fly south in the winter?