happened happening用法

What happened to my house? It becomes so messy! 我只是離開家裡兩個小時！ 我的房子發生什麼事了？它變得好髒亂。

= What occurred? 但這用於每天會發生的對話中會太正式，因此用happen會比較好。 ex. It all happened so fast ...

it happens that的用法和樣例：. 例句. How can it happen that so many machine parts get rusty? 怎麼竟會有這麼多機器零件 ...