Question

We must serve our country question tag

Answer 1

Answer:

It must be her car, isn't it?

It must be her car, right?

You must be tired, aren't you?

Why it can't be expressed:

It must be her car, mustn't it?

You must be tired, mustn't you?

Note:

Q:Is it her car?

A:Yes, it must be her car.

Possible tag question: It must be her car, isn't it?

Is it possible to ask: Must it be her car? (I've never used it though).

Do native speakers really avoid using tag question of "must"?

Answer 2

Should we serve our country?
This is your answer.