How to use a question word in a statement that isn't a question?

Question

I've been having trouble constructing statements containing question words. For example:

If you have a friend who can speak English

Most translation software writes this as.

如果你有一个能讲英语的朋友

Which sounds more like "If you have an English speaking friend" and completely leaves out the question word "who".

I was trying to construct sentences in a similar way to how they are said using the "When, 当。。。的时候” structure.

When I return home I'll give you phone call.

当我回家的时候我给你打电话

I only know how to say some other sentences this way such as.

I don't know when I should go.

我不认识, 我应该什么时候去

Is it possible to use other question words in this way? Or should the question word be left out and be said another way?

Other examples that I though of are.

1. She's the one who owns this car.
2. He told me what you said.
3. I will decide when I leave.
4. He will tell you where to go.
5. This is why I arrive early everyday.
6. This is how I use my phone.

Sorry for the long question and thanks in advance!

Answer 1

"If you have an English speaking friend" should be translated to 如果你有一个讲英语的朋友.

Here, 能讲英语的朋友 a friend who can speak English is much different from 讲英语的朋友 an English speaking friend, since there is a 能 which literally means can.

"I don't know when I should go" should be translated to 我不知道我应什么时候去.

Notice that 我不认识 usually means I don't know (who he/she is)

I'll try to both directly and natively translate your six sentences:

1. “She's the one who owns this car" 她是（这辆）车的主人
2. "He told me what you said" 他告诉了我你说了什么 他告诉了我你所说的话
3. "I will decide when I leave" 我将决定我什么时候离开 我将决定我离开的时间
4. "He will tell you where to go" 他将会告诉你（应该）去哪
5. "This is why I arrive early everyday" 这就是为什么我每天早到 这就是我每天早到的原因
6. "This is how I use my phone" 这就是我用自己手机的方式 我就是**这么**（accent）用手机的

Attributive clause or other forms of clauses exist in Chinese but are much different from English, they could be more implicit, differently structured. You can read this article: How to Translate English Attributive Clauses As a native Chinese speaker, I did not learn much Chinese grammar, so I suggest you find more in a textbook.

Answer 2

Here is a way to translate from the word-by-word method.

If you have a friend who can speak English

Word-by-word:

如果 你 有 一个 朋友 | 谁 能 说 英语

First pick the clause out and translate. Then you could understand that the part "who can speak English" describe the word "friend" which is 朋友 in Mandarin. To complete the translation, you put the "who can speak English" just in front of the word "friend", since in Mandarin the modifiers of objects are always put in front of the object. Finally you omit the question word [since in Mandarin there exists almost no clauses] and you have

如果你有一个 能说英语的 朋友

Same method could also applied to other sentences.

When I return home I will give you phone call

Word-by-word:

当 我 回 家 [的时候] | 我 会 给 你 打电话

Here the part "when I return home" describe the time. Then you could just leave it be. To be natural, you could omit "当" and the second "我", since the speaker and the audience know that the speaker, i.e. 我, would "give you phone call", hence you could omit this to be succinct. Finally you have

我回家的时候给你打电话。

or

我回家就给你打电话。

Other sentences:

1. 她 就是 人 | 谁 拥有 这辆 车 ==> 她就是拥有这辆车的人。 or 她就是这辆车的主人。
2. 他 告诉 我 | 什么 你 说过 ==> 他告诉我你说过什么。 or 他告诉我你说过的话。
3. 我 将 决定 什么时候 | 当 我 离开 [的时候] ==> 我离开的时候会决定这个时间。 [here we need more background to specify the first "when", otherwise the whole sentence would not be complete in meaning]
4. 他 会 告诉 你 | 哪里 去 ==>他会告诉你[要]去哪。
5. 这 是 | 为什么 我 到达 早 每天 ==> 这就是为什么我每天都早到。 or 这就是我每天早到的原因。 ["why" lead the cause, hence we translate the "cause" explicitly]
6. 这 是 | 怎么 我 用 我的 手机 ==> 这就是我怎么用我的手机。 or 这就是我用[我]手机的方式。 ["how" specifies the method or the way, and we translate it explicitly]