5 sentences

1. 我们要狠抓生产安全，绝不能掉以轻心。

   wǒ​men yào hěn​zhuā shēng​chǎn ān​quán, jué bù néng diào​yǐ​qīng​xīn.

   We must pay close attention to production safety and must not take it lightly.

   Source: Dong Chinese Dictionary

2. 他是一个狡猾的对手，千万不能掉以轻心。

   tā shì yī gè jiǎo​huá de duì​shǒu, qiān​wàn bù néng diào​yǐ​qīng​xīn.

   He is a cunning opponent; we must not let our guard down.

   Source: Dong Chinese Dictionary

3. 老板经常敲打他，以此提醒他不要掉以轻心。

   lǎo​bǎn jīng​cháng qiāo​dǎ tā, yǐ​cǐ tí​xǐng tā bù yào diào​yǐ​qīng​xīn.

   The boss often gives him a nudge to remind him not to become complacent.

   Source: Dong Chinese Dictionary

4. 汝等可知此举意味着什么，千万不可掉以轻心。

   rǔ děng kě​zhī cǐ jǔ yì​wèi zhe shén​me, qiān​wàn bù kě diào​yǐ​qīng​xīn.

   Do you all realize what this move signifies? You must not take it lightly under any circumstances.

   Source: Dong Chinese Dictionary

5. 虽然目的地已近在咫尺，但我们仍不可掉以轻心。

   suī​rán mù​dì​dì yǐ jìn​zài​zhǐ​chǐ, dàn wǒ​men réng bù kě diào​yǐ​qīng​xīn.

   Although the destination is close at hand, we still cannot let our guard down.

   Source: Dong Chinese Dictionary