2 sentences

1. 不要掉以轻心。

   bù​yào diào​yǐ​qīng​xīn.

   Don't let your guard down.

   Source: OpenSubtitles

2. 他知道任何对手都不能掉以轻心。

   tā zhī​dao rèn​hé duì​shǒu dōu bù​néng diào​yǐ​qīng​xīn.

   He knew that no opponent should be taken lightly.

   Source: OpenSubtitles