Confusion regarding 是不是，是 and 是……的

Question

I'm really confused about when 是不是 is used before verbs. (E.g. 你是不是忘了 我是谁了?）

From what I've been able to find out, it's used when you want to confirm something. Kind of like the "don't you?" in "you know, don't you?"

Does it always have the confirmational meaning? Or are there times when it's just a neutral question like 吗？

I also learned that 是。。。的 is used when you want to emphasize what comes after it.

If there's only the verb between 是 and 的 does it emphasize the verb?

And when you ask a question with this construction, does the question also have a confirmational meaning if the question is asked as 是不是。。。的? When are questions even asked using 是。。。的?

Lastly, I've learned that 是 is also used for emphasis like 是。。。的, but that it's meaning isn't restricted to the past.

Can this 是 have a verb following it?

And when making questions using 是不是 in order to emphasize something, does it also have a confirmational meaning, since it uses 是不是? Or can it be a neutral question?

Thank you in advance!

Answer 1

是：yes
不是：no
是不是：yes or no, whether or not, am I right, isn't it, are you

是不是 is easiest to understand as yes or no. How it gets translated depends on the context. Sometimes it won't be translated, because it is unnecessary in English.

查查你的尺码是不是有货。
Check whether or not your size is in stock.

真是令人惊叹，是不是？
That's amazing isn't it?

我是不是应该打电话向他道歉？
Should I call him and apologise?

Answer 2

From my perspective as a native speaker 是不是, and 对不对 are best understood as sort of a short form of "是，还是不是？" and "对，还是不对？". Those phrases or partial questions respectively mean "yes, or no" and "right, or wrong," and we often use them as replacements for "Is it yes or no?", "Am I right or wrong?", etc.

These partial questions can then be inserted into full questions or sentences in a similar way to English grammar, using "是不是" and "对不对" as a kind of word identical to the likeness of "right?" in questions.

For example: 这个也太便宜了，是不是？, or "This is too cheap, right?"

Note: One main difference between "是不是" and "对不对" is that there is one more way to use "是不是", being for emphasis. In a general way though, you can just treat it as the same for both, being similar to the word "right" in English.

For 是 and 是……的, just treat them as the literal meaning, "是" meaning yes.

Wish you luck!

Edit: Ah... I just saw the part about putting 是不是 before verbs. So for that, it is more of a confirmation, a bit like "is it true that". Sorry for the oversight.

Like you said, "Does it always have the confirmational meaning? Or are there times when it's just a neutral question like 吗？". This pretty much is a good idea to understand this, as 是不是 is often used similarly to 吗 (replace some questions with 是不是 before the verb with 吗 at the end and you'll get it).

Good luck again!