and和or的用法.有例句：Didhebuyarulerandapen?Didhebuyarulerorapen?这两句到底哪一句是对的呢?还有一组：Theydidn'tbuyarulerorapen.Theydidn'tbuyarulerandapen.

Question

and 和or的用法.
有例句：
Did he buy a ruler and a pen?
Did he buy a ruler or a pen?
这两句到底哪一句是对的呢?
还有一组：
They didn't buy a ruler or a pen.
They didn't buy a ruler and a pen.

Answer 1

解析：这两个句子都是对的,只是意思不同而已.
Did he buy a ruler and a pen?你买一把格尺和一本书了吗?（意思是两本都买了）
Did he buy a ruler or a pen?你买了一把格尺还是一本书?（意思是买了其中一个）
有不明白的请继续追问,