题目内容：

时间状语从句语序求解答.
As soon as the bell rang for the break,the door opened and in came Mr.Smith.
下课铃一响,门开了,史密斯先生走进来.
为什么最后一句in came Mr.Smith语序全颠倒了.参考书里找不到相关讲解,望专业老师指点.