那是你的妻子吗？would be a better translation; Is that your wife?
You use "是不是" to ask a question, when you already assume an answer.
So for example:
那是不是你的妻子？; Isn't that your wife?
你是不是要茶? ; Don't you want tea?
Why no ma?
Shi4 bu2shi4 is already indicated that it is a question.
When you ask a shi bu shi, x bu x, that is the questions, so ma is not needed.
Because 是不是 already makes it a question.
Why this app doesn't provide the pinyin system? It would be useful for vocabulary and pronunciation...
You can use this with a pinyin input method: just set up Chinese input in your computer settings.
Is 的 mandatory here? I put 那是不是你妻子
That indicates possession, so yes
It does indicate possession. However, when expressing close possession, it appears 的 may be omitted.
This is not a good translation. Should be asking : isn't that your wife? Since it's got a negative in the wording of the question
Wrong. "Isn't that your wife" would 那不是你的妻子吗?
是不是 is just a different way to ask a regular question which just deosn't require a 吗.
What about "这个是你的妻子吗？“ Does that work?
Yes! So much for using Ma when asking a yes or no question.
That way you would need 吗 .
Necessary to have na at the beginning?
Yes, I believe so.
Is there a way to let duolingo know that 的 is not used with close family/spouse?
I know the point of that lecture is probably to also get the 是不是 thing across, but wouldn't 这是你的妻子吗 also be a correct solution?
Yes you can ask it that way. Except here the question is asking "that" (那 = nà), not "this" :)