我不能相信你是说真的。

I can't believe you're serious.

Source: Tatoeba

Sentence Composition

1 我 wǒ
  1. I
  2. me
  3. my
2 不能 bùnéng
  1. cannot
  2. must not
  3. should not
3 相信 xiāngxìn to believe; to be convinced; to accept as true
=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 shì
  1. to be (followed by substantives only)
  2. correct; right; true
  3. (respectful acknowledgement of a command) very well
  4. (adverb for emphatic assertion)
=5 是 shì variant of 是 shì
6 说真的 shuōzhēnde
  1. to tell the truth
  2. honestly
  3. in fact