fánshì míngtiān tuìfáng de kèrén, dōu yào kàn tuìfángshíjiān.

凡是 means something like any, all, or whoever fits this condition.

In this sentence, it introduces a category:

• 凡是明天退房的客人 = all guests who are checking out tomorrow

It is often used when Chinese wants to say:

• everyone who...
• anything that...
• any person/item that meets a certain condition

So 凡是 is not just about one specific guest. It means the rule applies generally to that whole group.

They often work together as a pair:

• 凡是……都……

This pattern means:

• whenever / anyone who / anything that ... , all of them ...

In this sentence:

• 凡是明天退房的客人，都要看退房时间。

Structure:

• 凡是...的客人 = all guests who meet the condition
• 都 = marks that the statement applies to the whole group

So 凡是 sets up the category, and 都 says the following action applies to every member of that category.

This pairing is very common in Chinese.

This is a very common Chinese pattern where a verb phrase comes before 的 to describe a noun.

Breakdown:

• 明天 = tomorrow
• 退房 = check out
• 的 = turns the phrase before it into a modifier
• 客人 = guest

So:

• 明天退房的客人 = guests who will check out tomorrow

You can think of it as:

• [tomorrow check-out] + de + guests

This is like a relative clause in English, but in Chinese the descriptive part comes before the noun.

In Chinese, time words usually come before the verb they relate to.

So:

• 明天退房 = check out tomorrow

This follows a very common word order pattern:

• time + verb
• subject + time + verb
• subject + time + place + verb in many cases

Examples:

• 明天去 = go tomorrow
• 今天上班 = work today
• 下个月搬家 = move next month

So 明天退房的客人 literally has the sense of the guests who tomorrow check out.

Here, 的 links a descriptive phrase to a noun.

Pattern:

• [description] + 的 + noun

In this sentence:

• 明天退房的 describes
• 客人

So 的 is what allows 明天退房 to function like an adjective-like modifier.

Without 的, the phrase would not sound grammatical here.

Compare:

• 中国的客人 = Chinese guests / guests from China
• 昨天来的客人 = the guests who came yesterday
• 明天退房的客人 = the guests who will check out tomorrow

No, not in normal standard Mandarin.

You need 的 because 明天退房 is a verb phrase modifying 客人.

• correct: 明天退房的客人
• not natural: 明天退房客人

Chinese sometimes omits 的 in certain fixed expressions or very compact noun phrases, but with a full action phrase like this, 的 is normally required.

Here 要 does not mean want to. It means something closer to:

• need to
• must
• should
• are supposed to

So:

• 都要看退房时间 = all need to check the check-out time

This is a very common source of confusion because 要 has several meanings.

Common meanings of 要:

• want: 我要咖啡 = I want coffee
• need to / should / must: 你要早点睡 = you should sleep earlier
• be going to: 要下雨了 = it’s about to rain

In this sentence, the meaning is clearly obligation or necessity.

Yes, 看 literally means look at / read / check, and here it means check or look over the check-out time.

Chinese uses 看 in many situations where English might use:

• look at
• read
• check
• consult

So:

• 看退房时间 = check the check-out time

This is natural Chinese. Depending on context, English might translate it as:

• look at the check-out time
• check the check-out time
• pay attention to the check-out time

It is a compound noun made from:

• 退房 = check out
• 时间 = time

Together:

• 退房时间 = check-out time

Chinese very often forms nouns this way by combining smaller parts.

Similar examples:

• 上课时间 = class time
• 出发时间 = departure time
• 营业时间 = business hours
• 考试时间 = exam time

So even if you analyze it as parts, it functions as one noun phrase in the sentence.

The sentence structure is:

• 凡是 + condition + 的 + noun，都 + 要 + verb + object

Applied here:

• 凡是 = for all who meet the condition
• 明天退房的客人 = guests who check out tomorrow
• 都 = all of them
• 要看 = need to check
• 退房时间 = check-out time

So the full structure is:

• As for all guests who are checking out tomorrow, they all need to check the check-out time.

This is a useful pattern to remember because it can be reused easily.

Example:

• 凡是第一次来的人，都要登记。
• Everyone who comes for the first time must register.

Chinese often does not need a special future marker if the time word already makes the time clear.

Here, 明天 already tells us the action is in the future:

• 明天退房 = check out tomorrow

So adding something like English will is unnecessary.

Chinese often relies on:

• time words, such as 昨天, 今天, 明天
• context
• sometimes words like 会 or 要, if needed

But in this sentence, 明天 is enough.

Yes. This sentence is grammatical and clear, but 凡是 can sound a bit formal or rule-like.

Some more everyday alternatives might be:

• 明天退房的客人都要看一下退房时间。

• Guests checking out tomorrow should take a look at the check-out time.

• 如果你明天退房，要看一下退房时间。

• If you are checking out tomorrow, you should check the check-out time.

• 所有明天退房的客人都要看退房时间。
• All guests checking out tomorrow need to check the check-out time.

So the original sentence has a slightly general, announcement-like tone, which fits things like hotel notices or rules.