轻轻叹了口气在英语中可以表达为 "sigh softly" 或者 "give a soft sigh." 此短语来源于叹气，表示人因为某些原因感到不满或无助。例句包括：
She gave a soft sigh as she reapzed she had forgotten her keys. 她轻轻叹了口气，因为意识到自己忘了带钥匙。
I could hear him sigh softly on the other end of the phone. 我能听到他在电话另一端轻轻地叹气。
The pttle girl gave a soft sigh and fell asleep. 小女孩轻轻叹了口气，然后就睡着了。
希望这对您有所帮助。