mise ha mou simatte iru to omoimasu.

店は sets the store as the topic: as for the store...

So 店はもう閉まっていると思います means something like:

• As for the store, I think it’s already closed.

If you used が instead, it would sound more like you are identifying or emphasizing the store as the thing that is closed. In many everyday situations, は is the more neutral choice when the store is already the thing being talked about.

So:

• 店は... = speaking about the store as a topic
• 店が... = focusing more directly on the store as the subject

Both can be possible depending on context, but は is very common here.

もう means already here.

So 店はもう閉まっている means:

• The store is already closed

Be careful, because もう can also mean more in other contexts, but in this sentence it clearly means already.

閉まる is the dictionary form and means to close or to become closed.

But 閉まっている is the ている form, and with this kind of verb it often describes the resulting state.

So:

• 閉まる = to close / to become closed
• 閉まっている = is closed

In English, learners often expect ている to always mean is -ing, but that is not always true. Here it does not usually mean is closing. It usually means is in the state of having closed, or simply is closed.

In this sentence, it usually means is closed.

That is because 閉まる is an intransitive verb that describes a change of state. With many verbs like this, ている describes the state after the change has happened.

Compare the idea:

• door opens → open
• store closes → closed

So 店はもう閉まっている is normally understood as:

• The store is already closed

not

• The store is already in the process of closing

This is a very common question.

• 閉まる = to close / to become closed

  • intransitive
  • the thing closes by itself, or you focus on its state

• 閉める = to close something

  • transitive
  • someone closes it

Examples:

• 店が閉まる = The store closes
• 店を閉める = Someone closes the store

In your sentence, the focus is on the store’s condition, so 閉まっている is used.

The と marks the content of what someone thinks.

So X と思います means:

• I think that X

Here, the part before と is the thought:

• 店はもう閉まっている = the store is already closed

Then:

• 店はもう閉まっていると思います = I think the store is already closed

You can think of と here as linking the statement to 思います.

Because before と思います, Japanese normally uses the plain form, not です / ます form.

So:

• 店はもう閉まっている = plain-style clause
• 店はもう閉まっていると思います = I think the store is already closed

You would not usually say:

• 店はもう閉まっていますと思います ✘

That sounds unnatural.

This is a very important grammar pattern:

• plain clause + と思います

Examples:

• 雨が降ると思います = I think it will rain
• 彼は来ないと思います = I think he won’t come

The speaker is the one doing the thinking, so 私は is usually omitted because it is obvious from context.

Japanese often leaves out information that is understood.

So even without 私は, the sentence naturally means:

• I think the store is already closed

If you wanted to add it for emphasis or contrast, you could say:

• 私は店はもう閉まっていると思います

But in normal conversation, leaving it out is more natural.

思います means I think, so it sounds like an opinion, guess, or judgment rather than a hard fact.

So this sentence is softer than just saying:

• 店はもう閉まっている。 = The store is already closed.

By saying と思います, the speaker sounds less direct and more cautious:

• I think the store is already closed

This is very common in Japanese, where speakers often soften statements.

A casual version would be:

• 店はもう閉まっていると思う。

You may also hear the contraction:

• 店はもう閉まってると思う。

That is very natural in everyday conversation.

So the levels are roughly:

• 店はもう閉まっていると思います。 = polite
• 店はもう閉まっていると思う。 = casual
• 店はもう閉まってると思う。 = casual, conversational

The careful pronunciation is:

• しまっている

But in everyday speech, ている is often contracted to てる, so it often sounds like:

• しまってる

So you may hear:

• 店はもう閉まってると思います
• 店はもう閉まってると思う

This does not change the meaning; it is just a more natural spoken form.