英语问题Swallows(燕子） fly to the south before winter ( )1 will co

Swallows fly to the south before winter ( ) Swallows fly to the south before winter comes"he says. Swallows fly to the south before winter_____ Swallows fly to the south before winter comes .中文,为什么用comes而 初三英语习题The swallows know when __to fly __ south.为什么填 to fly , 连词成句.swallows ,in ,fly ,will,autumn ,to,south,the Some birds ( )to the south before winter When winter comes,some girds will fly to the south,__will st When autumn comes,swallows go to the south. 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 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