YOU SAID:

The not ask what the dog is doing

INTO JAPANESE

犬が何をしているのか尋ねない

BACK INTO ENGLISH

Don't ask what the dog is doing?

INTO JAPANESE

犬が何をしているのか聞かない?

BACK INTO ENGLISH

Why don't you ask what the dog is doing?

INTO JAPANESE

犬が何をしているのか聞いてみたらどうですか。

BACK INTO ENGLISH

Why don't you ask what the dog is doing?