Question

he fell down when he the bus

He fell down.He was running.(连成一句) He fell down____running.
填哪个词,at ,when,while.请解释选择的答案的理由,尤其when和while,

Answer 1

when与while都可以.
while与when经常被用在含有一般过去时及过去进行时的句子中.在这种情况,短的动作可以在长的动作过程中发生,即：长的动作发生在短动作前.while一般指相对长的动作；when即可以指相对长的动作也可以是指相对短的动作.在所给句子‘fell down’相对‘running’是短动作,因此,在这个句子里,‘when’ ‘while’都可以用.
通过以下句子也许可以进一步理
While he fell down,he was running 错,因为while只能指相对长动作
when he fell down,he was running 对,因为when 可指长或短动作
He fell down,when he was running 对,因为when 可指长或短动作
He fell down,while he was running 对,因为while 指相对长动作