The door burst open and in rushed the crowed.解释一下这里为什么要全部倒装?

部分副词和动词可以直接构成全部倒装句,其句型是：
副词+动词+主语（名词时）.In came Mr wang,our English teacher.
Here comes the bus.There goes the bell.
副词有：up down in out here there away off
动词有：come go run rush jump sit lie fly float be
注意下列句型,副词在句首时,不需要主谓倒装：
副词+主语（人称代词时)+谓语.
Here we are.Here it is.