mushiba ga arimasu.

subject particle

Breakdown of mushiba ga arimasu.

• ある: to exist
• 虫歯むしば: a cavity; tooth decay

Questions & Answers about mushiba ga arimasu.

Why is が used here?

が marks 虫歯 as the thing that exists.

So 虫歯があります literally means something like A cavity exists or There is a cavity.

In natural English, when talking about your own body, that often becomes I have a cavity.

This is a very common Japanese pattern:

• 時間があります = I have time
• お金があります = I have money
• 問題があります = There is a problem / I have a problem

So が is not marking a direct object here. It is marking the noun that goes with ある.

Why is it あります and not います?

Japanese uses:

• ある / あります for things that are not alive or are treated as inanimate
• いる / います for people and animals

A cavity, 虫歯, is not a living thing, so Japanese uses あります.

For example:

• 猫がいます = There is a cat.
• 本があります = There is a book.
• 虫歯があります = There is a cavity / I have a cavity.

Why doesn’t this sentence say 私は?