"that" in Mandarin joining clauses or sentences?

Question

Can someone help me understand how to say "that" in the following uses? Please provide pinyin in your answer, since my characters aren't so good :(

• He is the one THAT I saw.
• It's the one THAT I want.
• They said THAT they would come.

Answer 1

The word "that" in your third example actually doesn't introduce a relative clause. Rather it's being used as a subordinating conjunction. In this situation, the word "that" is generally optional in English, and it also is similarly omitted in Chinese:

They said [that] they would come.

他们说他们会来。

Tāmen shuō tāmen huì lái.

Relative clauses generally describe a noun or noun phrase (known as the antecedent). In Chinese, while 的 de is often used to indicate possession, it more generally is used to link a description to a noun or noun phrase, and thus can similarly be used to introduce a relative clause. When the noun or noun phrase being described is understood in context, it is omitted, leaving simply description + 的.

Let's look at your first example:

He is the one that I saw.

The relative clause is "I saw", which is simply 我看见 wǒ kànjiàn. In English the noun being described cannot be omitted when "that" is used to introduce the clause, which is why the word "one" appears to serve as the placeholder. In Chinese, it can be omitted, so "the one that I saw" ends up being simply 我看见的 wǒ kànjiàn de, thus:

He is the one that I saw.

他是我看见的。

Tā shì wǒ kànjiàn de.

If instead there was a specific noun, such as "person" instead of "one", you would have:

He is the person that I saw.

他是我看见的人。

Tā shì wǒ kànjiàn de rén.

Applying the same principles to your second example:

It's the one that I want.

它是我想要的。

Tā shì wǒ xiǎngyào de.

EDIT - Addendum:

Note that in English the noun being described can be omitted if you instead use a relative pronoun to introduce the relative clause rather than using the word "that". So instead of "He is the one that I saw" and "It's the one that I want", you could say "He is who I saw" and "It's what I want". The former have what are known as bound relative clauses while the latter have free relative clauses. The word "that" can only be used in bound relative clauses.

I just wanted to add this note to let you know that when you see a free relative clause, you can translate it to Chinese similarly, e.g.:

I like what he sees. (i.e., I like the one that he sees.)

我喜欢他看见的。

Wǒ xǐhuān tā kànjiàn de.

Answer 2

You don't need to use a relative pronoun in this case. The 的 construct serves as a prenominal adjectival phrase replacing the English concept of the relative pronoun.

He is the one that I saw.

他是我看見的（人）。

Tā shì wǒ kànjiàn de (rén).

It's the one that I want.

它是我想要的（東西）。

Tā shì wǒ xiǎng yào de (dōngxi).

The last case isn't the same - "that" in this case is a way of highlighting an indirect quotation, and actually isn't grammatically necessary in English at all.

They said (that) they would come.

他們說他們會來。

Tāmen shuō tāmen huì lái.

Answer 3

The fact is that there is no Clause in Chinese grammar. The choices for you are:

(1) Separate to two sentence and use conjunction words. For example:

He is the one THAT I saw

-> I saw him. He is the one.

-> Wo3 Jian4 Dao4 Ta1 Le. Ta1 (Jiu4) Shi4 (Na4 Ge4) Ren2.

(2) Change to adjective or adverb, depends on the meaning of the sentence. For example:

It's the one THAT I want.

-> It is the expected thing.

-> Zhe4 Shi4 Wo3 Xiang3 Yao4 de Dong1 Xi1. de is most used for adjective.

(3) Use :"" or just : for what it said. For example:

They said THAT they would come.

-> They said : they would come.

-> Ta1 Men2 Shou1 Guo4 : Ta1 Men2 Hui4 Lai2.