2 sentences for 确定 (què​dìng — definite)

1. 他并没有给我一个确定的时间。

   tā bìng méi​yǒu gěi wǒ yī gè què​dìng de shí​jiān.

   He didn't give me a definite time.

   Source: Dong Chinese Dictionary

2. 面对这种不确定的情况，我们不能盲目冒险。

   miàn​duì zhè zhǒng bù què​dìng de qíng​kuàng, wǒ​men bù néng máng​mù mào​xiǎn.

   Faced with such uncertainty, we cannot take blind risks.

   Source: Dong Chinese Dictionary