carefully的比较级和最高级分别是more carefully和most carefully。carefully意思是1、仔细的，小心的，认真的，谨慎的；2、准确的，精确的，精心的；3、苦干的，刻苦的，切实的；4、关心的，关切的；5、吝啬的，小气的。carefully是副词，作状语，修饰动词或整个句子。
例句：He unpacked the doll carefully from its box。他小心地把玩偶从盒子里取出来。He reads the book carefully。他仔细地阅读这本书。You should drive more carefully than you cycle。你开车比骑车更要谨慎。
He listens to the teacher more carefully than others。他比别人更认真地听老师讲课。Mary is the most carefully at work。玛丽工作最细心。He drives most carefully at night。他晚上开车非常小心。