wǒmen yìqǐ chàng ba.

Mandarin often expresses let’s ... as 我们 + verb + 吧.

So instead of using a separate word meaning let’s, Chinese commonly says something like:

我们唱吧 = Let’s sing

Here, 我们 literally means we/us, but in this pattern it helps create the sense of let’s.

吧 is a very common sentence-final particle. In this sentence, it makes the tone sound like a suggestion, invitation, or gentle proposal.

So:

• 我们一起唱。 can sound more like a plain statement: We sing together / We will sing together
• 我们一起唱吧。 sounds like Let’s sing together

It usually does not have one perfect English translation by itself. Its job is more about the speaker’s attitude.

一起 means together, and here it functions like an adverb, so it normally comes before the verb.

Basic pattern:

subject + adverb + verb

So:

• 我们一起唱吧。
• 我们一起去吧。
• 大家一起学中文。

This is different from English, where together can sometimes move around more freely.

This is because 一 changes tone depending on the word that follows it.

Its basic tone is first tone: yī.
But in normal speech:

• before a fourth-tone syllable, it becomes yí
• before a non-fourth-tone syllable, it becomes yì

Since 起 is third tone (qǐ), 一 becomes yì:

• 一起 → yìqǐ

This is a standard tone change rule, and learners see it very often.

Usually 我们 is pronounced wǒmen, with 们 in a neutral tone.

So it sounds more like:

• wǒ men

not a strong, fully stressed wǒ mén.

This neutral tone makes the word sound more natural in connected speech.

Yes. Both are possible.

• 唱 = to sing
• 唱歌 = to sing songs / to sing

In many situations, 唱 by itself is perfectly natural, especially when the context is clear.
But 唱歌 can sound a little more explicit to learners because it clearly includes the idea of singing songs.

So these are both fine:

• 我们一起唱吧。
• 我们一起唱歌吧。

They are similar, but not exactly the same.

• 我们 = we
• 咱们 = we, but it very clearly includes the listener

In invitations like this, 咱们一起唱吧 is also very common and often feels especially natural in spoken Chinese.

So:

• 我们一起唱吧 = Let’s sing together
• 咱们一起唱吧 = Let’s sing together, with a stronger feeling that you and I are included together

Yes, often it can be, if the context is clear.

For example:

• 一起唱吧。 = Let’s sing together.
• 唱吧。 = Sing / Let’s sing.

Chinese often drops subjects when they are understood from context.
Keeping 我们 makes the invitation more explicit and can sound a bit warmer or clearer.

It is usually understood as a suggestion or invitation, not a harsh command.

That softer feeling comes mainly from 吧. Without 吧, the sentence could sound more direct or simply descriptive, depending on context.

So 我们一起唱吧 is like saying:

• Let’s sing together
• Come on, let’s sing together

It sounds encouraging rather than forceful.

A useful way to see it is:

subject + adverb + verb + particle

In this sentence:

• 我们 = subject
• 一起 = adverb
• 唱 = verb
• 吧 = sentence-final particle

So the structure is:

我们 + 一起 + 唱 + 吧

This is a very common and useful pattern in beginner Mandarin.