3 sentences

1. 千万别失了这次出国的机会。

   qiān​wàn bié shī le zhè cì chū​guó de jī​huì.

   Don't miss this opportunity to go abroad.

   Source: Dong Chinese Dictionary

2. 他在混乱中失了包裹，非常着急。

   tā zài hùn​luàn zhōng shī le bāo​guǒ, fēi​cháng zháo​jí.

   He lost his package in the chaos and was very anxious.

   Source: Dong Chinese Dictionary

3. 说话办事要注意分寸，不能失了度。

   shuō​huà bàn​shì yào zhù​yì fēn​cun, bù néng shī le dù.

   One must be mindful of propriety in words and deeds and not lose one's sense of measure.

   Source: Dong Chinese Dictionary