のReplacing an understood noun
の can replace a specific person or thing that is already clear from the context. Depending on the sentence, English may use “one,” “ones,” “mine,” or a similar expression.
Leave out only what is already clear
The clearest beginner pattern is a noun followed by の. For example, once an umbrella has been mentioned, the full phrase 田中さんの傘 can become 田中さんの. The missing noun is understood from the question or nearby sentence.
Avoiding repetition
The answer does not repeat the word for “umbrella” because the question has already established it.
The shortened phrase can take another particle
The phrase ending in の behaves like the omitted noun phrase. Add を, が, or は according to the role of the whole phrase in the sentence.
どの傘を使いますか。田中さんのを使います。
Which umbrella will you use? I will use Tanaka's.
Analyzeの replaces the understood umbrella, and を marks the resulting phrase as the object.
Adjectives and clauses can identify the missing noun
The same replacement is possible after an adjective or a clause that tells the listener which concrete person or thing is meant. With a na-adjective, keep な before の.
Different kinds of modifier
Concrete thing, event, or focus?
If an actual noun follows の, nothing has been omitted: it is ordinary noun-to-noun modification. If の turns an action or event into a noun-like expression, that is a different use from the concrete-noun replacement taught here. A sequence containing のは may also belong to the separate focus pattern; decide from what the sentence is doing, not from the surface form alone.
More examples
ケーキが三つあります。千円のを注文しました。
There are three cakes. I ordered the thousand-yen one.
Analyze新しい写真と古い写真があります。古いのを見せてください。
There are new photos and old photos. Please show me the old ones.
Analyzeこのコートは姉のです。
This coat is my older sister's.
Analyze今年のカレンダーはここです。去年のは箱に入っています。
This year's calendar is here. Last year's is in the box.
Analyze鍵が二つあります。大きいのが玄関の鍵です。
There are two keys. The large one is the front-door key.
Analyze棚に皿が何枚かあります。白くて丸いのを取ってください。
There are several plates on the shelf. Please take the white, round one.
Analyze