____________, the car stopped all at once.

______, the car stopped all 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

____________, the car stopped all at once.

       A．Seeing a boy lying on the road

       B．On seeing a boy sitting on the road

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

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

_____, the car stopped all at once.

A．Seeing a boy lying on the ground

B．On seeing a boy sitting on the road

C．The driver saw a boy standing on the road

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

________， the car stopped all at once.