They lost their way in the forest and this

问题描述:

They lost their way in the forest and this
made matters worse was that night began to fall.
this处能用what吗?
如果用what怎么改?

本来就该用WHAT,用WHAT指代night began to fall
而且还有一个固定用法就是 WHAT'S WORSE意为更糟的是……