It was ______ of him to have broken a vase while he was shopping

It was ______ of him to have broken a vase while he was shopping in the supermarket. （care）
【正确答案】：careless
【题目解析】：此处需要填入作表语的词，故要用形容词。根据句意要用表示否定的careless而不是表示肯定含义的careful。