You can also use "whom", but it's not so common, "whom" would be the indirect version of this, someone who's not doing something.
你们还可以用" whom"，但是" whom"并不是很常用，" whom"是" who"的宾格形式，不能在句子中充当主语。
Now, you'd use "that" when you're describing things. Okay?
"I went to Bath on Saturday that was a fantastic place to visit." Okay?
比如 " I went to Bath on Saturday that was a fantastic place to visit. " （我周六去了巴斯，那是个游玩的好地方），
So I'm describing the activity of going to a place. Okay?
Bath itself. Okay? So it's a proper noun.
"Which" I can throw in there when I want to also describe things in a non-defining clause sense.
"The film which I saw on Saturday was really good." Okay?
比如 "The film which I saw on Saturday was really good."（我星期六看的那部电影非常棒），
You can get some more information on this on another one of our videos.
"Whose" when I'm describing a possession. So, "The car I drove whose owner was Charlie." -- okay?
在描述所有权时，可以使用" whose"。比如 "The car I drove whose owner was Charlie." （我开的那辆车是Charlie的）。
So I'm describing an element of possession. Okay?
Now, looking onto the relative adverbs. I can use "when" when I'm talking about times.
"I went to school when I was aged 13 to 18." Yeah?
比如 "I went to school when I was aged 13 to 18." （我13到18岁的时候都在上学）。
I can use "where" when I'm talking about the place that something happens.
So "I went to the actor's temple, where I learnt a lot about acting." Okay?
比如 "I went to the actor's temple, where I learnt a lot about acting."（我去了电影学院，在那儿学到了很多关于表演的知识）。
So giving more information about that particular place.
And I can use "why" ,I mean, "why" normally results in a question.
It's difficult to include "why" and then end in a full stop.
我们很少把" why" 用在肯定句中。