搞不懂英语从句 包括那些that when who 在句子里的意思和用法都不懂.

that 用于物,人和东西皆可以,或者引导主语从句；如That it costs too much scares me 。
when 用于时间,也就是做时间的定语从句时用它；I got up at 6 when I hear the alarm
who用于人,前面是人用它 How do you like the new teacher who always carries a cup。