掉以轻心

dà dí dāng qián wǒ men bù néng diào yǐ qīng xīn

大敌当前，我们不能掉以轻心。

Faced with a formidable enemy, we must not lower our guard.

duì jiāo tōng guī zé bù néng diào yǐ qīng xīn

对交通规则不能掉以轻心。

We must not ignore traffic regulations.

zhè chǎng dòu zhēng shì fù zá de wǒ men jué bù kě diào yǐ qīng xīn

这场斗争是复杂的，我们决不可掉以轻心。

This struggle is complex. We can never let down guard.

duì yú zhè ge wèn tí wǒ men kě bù néng diào yǐ qīng xīn

对于这个问题我们可不能掉以轻心。

This is not a problem we should take lightly.