我無法分辨你是否在開玩笑。

I can't tell if you're joking.

Source: Tatoeba

Sentence Composition

1 我 wǒ
  1. I
  2. me
  3. my
2 無法 wúfǎ unable to; incapable of
3 分辨 fēnbiàn
  1. to distinguish; to differentiate
  2. to resolve
=4 你 nǐ you (informal, as opposed to courteous 您 nín)
=4 你 nǐ you (Note: In Taiwan, 妳 is used to address females, but in mainland China, it is not commonly used. Instead, 你 is used to address both males and females.)
5 是否 shìfǒu
  1. whether (or not)
  2. if
  3. is or isn't
6 在 zài
  1. to exist; to be alive
  2. (of sb or sth) to be (located) at
  3. (used before a verb to indicate an action in progress)
7 開玩笑 kāiwánxiào to play a joke; to make fun of; to joke