回答

・don't let your guard down
・you must be careful

「不能掉以輕心」在英語中可以用don't let your guard down 或
you must be careful來表達。

Don't let your guard down when things are going well.
（事情進展順利時也不能掉以輕心。）

Your opponent will never give up until the end, so you must be careful!
（對手到最後都不會放棄，所以你不能掉以輕心！）

有幫助｜0