Tôi mời cả cậu và Lan.

In this sentence, mời means to invite.

So Tôi mời cả cậu và Lan means I invite both you and Lan.

A useful note: mời can also mean to offer politely, depending on context. For example, it can be used when offering food, drinks, or asking someone to do something politely. But in this sentence, the natural meaning is invite.

Cả adds the meaning of both.

So:

• Tôi mời cậu và Lan = I invite you and Lan
• Tôi mời cả cậu và Lan = I invite both you and Lan

It emphasizes that the invitation includes the two people together, not just one of them.

In Vietnamese, cả often goes before the group or list that it includes.

So cả cậu và Lan literally works like:

• both you and Lan

This is a normal pattern:

• cả A và B = both A and B

You do not usually repeat cả before each item.

Cậu is a personal pronoun used for you in certain social relationships. It is fairly informal and depends on age, closeness, and context.

It is commonly used:

• between friends
• for someone of a similar age
• sometimes when speaking to a younger person, depending on the speaker’s pronoun system

Vietnamese pronouns are very relationship-based, so cậu is not a universal word for you. In another situation, the speaker might use bạn, anh, chị, em, or something else instead.

Tôi is a neutral and fairly standard way to say I.

It is common when:

• speaking politely
• speaking neutrally
• not using a more relationship-specific pronoun

Yes, it is more neutral and somewhat more formal than some other first-person pronouns. In close conversation, a speaker might use another pronoun instead, depending on the relationship.

So Tôi mời cả cậu và Lan sounds grammatically normal and socially neutral, though the exact naturalness depends on who is talking to whom.

The word order is very similar to English here:

• Tôi = I
• mời = invite
• cả cậu và Lan = both you and Lan

So Vietnamese is basically:

• I invite both you and Lan

This makes the sentence quite straightforward for English speakers.

Normally, when connecting two nouns in this pattern, và is the standard word for and:

• cả cậu và Lan = both you and Lan

Without và, the sentence would sound incomplete or unnatural in standard Vietnamese.

There are other ways to express a similar idea, such as:

• Tôi mời cả cậu lẫn Lan
• Tôi mời cậu với Lan in some casual/regional speech

But in standard Vietnamese, cả ... và ... is a very common and clear pattern.

Both can mean that the speaker invites the two people, but cả adds emphasis.

• Tôi mời cậu và Lan = I invite you and Lan
• Tôi mời cả cậu và Lan = I invite both you and Lan

With cả, the speaker is more clearly stressing that the invitation includes the two of you together.

Yes. Mời is broader than English invite in some situations.

Depending on context, it can mean:

• invite someone somewhere
• invite someone to an event
• offer someone food or drink
• politely ask someone to do something

For example, if people are talking about going out to eat, Tôi mời cả cậu và Lan could imply something like I’m treating both you and Lan or I’m inviting both you and Lan out. Context decides the most natural English translation.

Sometimes yes, if the subject is already clear from context.

For example, in conversation, someone might simply say:

• Mời cả cậu và Lan.

But in a full, clear sentence, especially for learners, Tôi mời cả cậu và Lan is better because it explicitly includes the subject I.

Vietnamese often drops subjects when they are obvious, but keeping them makes the sentence easier to understand.

Yes. Vietnamese does not use articles like a or the in the same way English does.

A proper name like Lan just appears directly:

• Lan

No article is needed.

That is completely normal in Vietnamese.

That depends on the relationship, but Vietnamese often uses more relationship-specific pronouns than tôi.

For example, close friends of similar age might say something like:

• Tớ mời cả cậu và Lan.

Here:

• tớ = a casual I
• cậu = a matching casual you

So compared with tôi, tớ can sound friendlier and more natural in close informal speech.

Cả ... và ... explicitly names the two items:

• cả cậu và Lan = both you and Lan

Cả hai means both or the two of them, but it usually refers to two people already understood from context.

For example:

• Tôi mời cả hai. = I invite both of you / both of them

So if you want to name the people directly, cả cậu và Lan is the clearer form.