"यह मत करो!"

Translation: Do not do this!

[_decca_]

I wrote "don't do this". There's no option to report it right now but it should be accepted.

[wihlke]

Next time it comes up, write that sentence and you’ll get the option to report by “my sentence should be correct” or similar. It only shows when your answer is rejected.

[Sarah_130408]

Mine was accepted

[AparnaV10]

Ya it should be accepted

[icanconfirm]

Similarly, what is wrong with "यह नहीं करो!" ? Thanks

[AnUnicorn]

The other comments I've seen from (presumably) native speakers just say "I don't know why, but we just don't do it that way."

I guess तुम just has an active aspect of "don't do!" while नहीं is more of a statement of "is not"?

[LangPhile]

And also the fact that:
नहीं करो।
Can mean: No, just do it.
मत करो।
Can not mean: No, do it.

[LangPhile]

And that
नहीं would need a comma.
But I'd use both to mean the same though!

[LangPhile]

Yes and no!
We tend to use
मत when we make imperatives, in assertion, we use both sometimes:
मैंने कहा नहीं करो। = I said, "Don't do."
मैंने कहा मत करो।= I said, "Don't do."

[ragingfire4]

With the 1st, given the correct emphasis (pause b/w nahi and karo), it can also mean "did I not say, do it" (i.e. I've already instructed/ordered you to do this, so do it right now)

[Viv1891]

Using ...."Nahi karo" is another option... however NAHI KARO is more commonly used with AISA / WAISA = LIKE THIS / LIKE THAT rather than with YAH/WAH. It conveys the same meaning, probably passively.
The use of MAT impicitly induces an authority and goes with the imperative tone of the speaker. This lesson being imperative speech has probably resorted to teach the word MAT.