是不是
shì​bu​shì HSK1

is it or not

Senses

是不是 shì​bu​shì (also shì​bù​shì) is it or not

Used to ask for confirmation or to form a question about whether something is true; is it the case that...; isn't it?

是不是 shì​bu​shì (also shì​bù​shì) whether or not

Used to express a choice or uncertainty between two possibilities.

是不是 shì​bu​shì (also shì​bù​shì) at any time

(Literary) frequently; regardless of the occasion; at any moment (often suffixed with 的 de)

是不是 shì​bu​shì (also shì​bù​shì) perhaps

Used as an adverb to express uncertainty or a tentative guess; maybe; possibly

References

synonym 是否/是否 → 是不是/是不是
synonym 莫不是/莫不是 → 是不是/是不是