2 sentences

1. 成功率很低，但不是零。

   chéng​gōng​lǜ hěn dī, dàn bù​shì líng.

   The success rate is low but not zero.

   Source: CCMatrix

2. 很难说成功率如何。

   hěn nán​shuō chéng​gōng​lǜ rú​hé.

   It’s hard to say what the success rate is.

   Source: CCMatrix