—Can you describe it happened?
—Yes, I was riding on my bike a car knocked me down from behind.
A. when; as
B. how; as
C. how; when
D. how; while
网友回答
A. when; as
B. how; as
(答案→)C. how; when
D. how; while
解析：考查连词。how怎么；be doing … when …正在做……突然…….，句意：——你能描述它怎么发生的吗？——好的，我正在骑自行车的时候，突然一辆小汽车从后面撞到了我。