是否

shìfǒu

adverb HSK 4 #521

Meanings

Yes + no = yes or no, used to ask whether something is the case.

HSK 4

是否参加由你决定。

Shìfǒu cānjiā yóu nǐ juédìng.

Whether to participate is up to you.

HSK 5

请确认是否收到邮件。

Qǐng quèrèn shìfǒu shōudào yóujiàn.

Please confirm whether you received the email.

HSK 5

我不确定他是否同意。

Wǒ bú quèdìng tā shìfǒu tóngyì.

I'm not sure whether he agrees.

usage

是否 is more formal/written than 是不是. Use 是否 in formal writing and emails.

是 shì

否 fǒu