区分and、but、orand 表示“和”，用在肯定句中，连接两个并列的部分I have a brother and a sister. 我有一个哥哥和一个姐姐。I have two pens and three rubbers. 我有两支钢笔和三块橡皮。or 1.
She is beautiful， but she is mean. 她很漂亮，但她很小气。Although she loves me， yet she refused me. 虽然她爱我，但她拒绝了我。
