It当需主词用时，是否可以利用These / Those / This / that取代?
例如
Today is fine. It makes me happy.
可以改成以下状况吗?
Today is fine. This(These/Those/This/That) makes me happy.
另外，虽然我知道this/that是单数的代名词，these/those是复数的代名词
但想请问
针对一件事的代名词要用单数或是复数
还有，这(this)或是那(that)在距离不是很清楚的状况下，
是不是可以混用?
对于这四个Th的用法不甚了解
还请各位帮忙解惑
谢谢！

today is fine 很少人这么用的，概念上 fine 不会描述时间时间通常会被描述成“长或短”之类的，好不好则是指事情譬如 the weather today is fine, it's fine today...this makes me happy 满常听到的，指前面的整句，参考：https://youglish.com/pronounce/this%20makes%20me%20happy