The dogs are sent out into the snow( )a traveller is in difficulty.
A if ever B in case C all the time Dwhile
答案是A。
疑问:D为什么不对?
The dogs are sent out into the snow( )a traveller is in difficulty.
A if ever B in case C all the time Dwhile
答案是A。
疑问:D为什么不对?
while引导时间状语从句,主句应用进行时态