Complete the sentences with the given words in their proper forms（用括号中所给单词的适当形式完成下列句子）：

【1】Aristotle（亚里士多德）was one of the most famous ________ in the world. （think）

【2】Some students might spend most of their holiday time in ________ places. （amusing）

【3】Dad, do you know smoking is harmful to your ________? （healthy）

【4】Peter ________ didn’t know Kitty’s phone number. （real）

【5】In some north ________, coal is mainly used for heating. （city）

【6】A ship sank last month and many people ________ in the accident. （dead）.