下面这两句话的to 是什么意思，请高手指点下，万分感谢

Question

they are under great pressure because of the final exam which will decide their lives to a great extent
和so some music may ease their pressure and help them to better their personality
这两句中to 是什么含义阿

Answer 1

they are under great pressure because of the final exam which will decide their lives to a great extent

to 是介词，表示达到的意思。
so some music may ease their pressure and help them to better their personality

这里的to是不定式，better 是动词，表示目的，意思是使个性变得更好。

Answer 2

第一个to a great extent 很大程度上，非常，是固定搭配，to是介词；
第二个to do不定式

Answer 3

to是个介词，一般不具有实质意义，第一个to，是decide to，属于固定搭配，第二个to其实可以省略，help sb do sth。to后面一般接动词原型