她粗心大意地把钥匙落在了家里。

She left the keys at home because of her ___careless behavior.

他一句不经意的评论让整个房间陷入了尴尬的沉默。

His ___careless comment caused an awkward silence in the room.

他因为粗心大意把咖啡洒在了重要文件上。

He spilled coffee on the important documents due to his ___careless behavior.

孩子们在公园里无忧无虑地玩耍。

The children played in the park with ___careless joy.