ful carefully 小心謹慎地 [Card #26; 字卡第26張: 第2個單字]

ful: a suffix meaning "full of"
Some more examples(更多例字):tactful, handful, thankful, flavorful, grateful, ungrateful, graceful, disgraceful, tasteful, distasteful, wasteful, playful, painful, faithful, unfaithful, careful, armful, harmful, watchful, awful, healthful, helpful, plentiful, restful, respectful, disrespectful, successful, unsuccessful, stressful, deceitful, peaceful, meaningful, fearful, cheerful, willful, skillful, blissful, pitiful, rightful, frightful, delightful, insightful, colorful, wonderful, hopeful, forceful, forgetful, thoughtful, resourceful, joyful, powerful, mouthful, doubtful, youthful, roomful, spoonful, cupful, trustful, truthful, fruitful, useful, beautiful, merciful, purposeful