Question

______, so he stopped the car at once.

A．Seeing a boy lying on the road

B．On seeing a boy sitting on the road

C．The driver had seen a boy standing on the road

D．The minute the driver saw a boy seated on the road

Answer 1

C

考查状语从句，句意：这名司机看到一个男孩站在在公路上，因此他立刻停下来。这是一个原因状语从句，后面已经有了so，前一个分句不能出现because，所以选C。