Yêu cầu và khiếu nại ở trong email.

Vietnamese often leaves out to be when it links a subject to a location, quality, or identity in simple statements.

So:

• Yêu cầu và khiếu nại ở trong email. = The requests and complaints are in the email.

Here, ở trong already gives the idea of location, so no separate verb like are is needed.

A very natural way to think about it is:

• [thing] + [location]
• requests and complaints + in the email

This is completely normal in Vietnamese.

Ở trong means in / inside.

• trong = in, inside
• ở often adds a sense of being located at/in

So ở trong email means in the email.

In many cases, ở trong and trong are both possible:

• Yêu cầu và khiếu nại trong email.
• Yêu cầu và khiếu nại ở trong email.

Both can work, but ở trong can sound a little more explicitly locational, like are located in the email.

In casual everyday Vietnamese, speakers often shorten it to just trong email.

Here, yêu cầu is a noun, meaning something like request or demand, depending on context.

That is very common in Vietnamese: many words can function as either verbs or nouns depending on position and context.

For example:

• Tôi yêu cầu đổi hàng. = I request an exchange.

  • Here yêu cầu is a verb.

• Yêu cầu của khách hàng rất rõ. = The customer's request is very clear.

  • Here yêu cầu is a noun.

In your sentence, because it is paired with khiếu nại and used as the subject, it is understood as a noun.

Yes. Khiếu nại can also be either a verb or a noun.

• As a verb: to complain
• As a noun: a complaint

Examples:

• Tôi muốn khiếu nại. = I want to complain.
• Khiếu nại của khách hàng đã được xử lý. = The customer's complaint has been handled.

In Yêu cầu và khiếu nại ở trong email, it is a noun, because it is part of the noun phrase requests and complaints.

Và means and. It connects two nouns:

• yêu cầu = requests
• khiếu nại = complaints

So:

• Yêu cầu và khiếu nại = requests and complaints

This works just like English and in a simple list.

Vietnamese does not use articles the same way English does. There is no direct equivalent that must always appear before nouns.

So yêu cầu và khiếu nại could mean:

• requests and complaints
• the requests and complaints
• sometimes even some requests and complaints

The exact meaning depends on context.

If the speaker wanted to make the nouns more explicitly definite or specific, they might add classifiers or other context, but in many sentences Vietnamese simply leaves that unstated.

You usually know from context, not from the noun form itself.

In this sentence, email could mean:

• the email
• an email
• less likely, a general email context depending on the situation

Vietnamese nouns normally do not change form for singular or plural.

If the speaker wanted to be more specific, they could add words such as:

• một email = one/an email
• những email = emails
• các email = emails

But without those markers, you rely on context.

Yes. Vietnamese often leaves definiteness unspecified.

So this sentence could be translated in more than one natural way, depending on context:

• The requests and complaints are in the email.
• Requests and complaints are in the email.

If the conversation already mentioned certain requests and complaints, the is likely best in English. If it is more general, no article may sound better.

Yes, it can be a complete sentence, especially in context.

Vietnamese often allows compact sentences where English would expect more structure. If the situation is already clear, this sentence sounds like a straightforward statement of where the requests and complaints are.

That said, depending on context, native speakers might also say slightly fuller versions such as:

• Yêu cầu và khiếu nại nằm trong email.
• Các yêu cầu và khiếu nại ở trong email.
• Yêu cầu và khiếu nại có trong email.

These versions may sound a little more explicit, but your original sentence is still understandable and acceptable.

They are related but not identical.

• trong = in
  • simple and common
• ở trong = be in / be inside
  • more clearly locational
• nằm trong = literally lie in, but often means be contained in / be included in
  • slightly more formal or descriptive in some contexts

Examples:

• Thông tin trong email = the information in the email
• Thông tin ở trong email = the information is in the email
• Thông tin nằm trong email = the information is contained in the email

So for your sentence, ở trong emphasizes location, while nằm trong could emphasize that the content is contained within the email.

Yes. Vietnamese speakers commonly use email, but you may also see:

• thư điện tử = email, electronic mail

So you could say:

• Yêu cầu và khiếu nại ở trong thư điện tử.

However, in real everyday usage, email is extremely common and often sounds more natural than the fully Vietnamese term.

Because Vietnamese nouns usually do not change form for plural.

The words:

• yêu cầu
• khiếu nại

can mean either singular or plural depending on context.

English requires a choice between request/requests and complaint/complaints, but Vietnamese often leaves that open.

If needed, Vietnamese can mark plural with words like:

• những
• các

For example:

• Các yêu cầu và khiếu nại ở trong email. = The requests and complaints are in the email.

But plural marking is often optional when the meaning is already clear.

Sometimes, yes.

• ở trong email focuses on location: the requests and complaints are in the email.
• có trong email focuses more on existence/presence: the email contains requests and complaints.

Compare:

• Yêu cầu và khiếu nại ở trong email. = The requests and complaints are in the email.
• Có yêu cầu và khiếu nại trong email. = There are requests and complaints in the email.

So both are possible, but they highlight slightly different things. Your sentence is more about where the requests and complaints are located.