1) 並列結構中，or通常用於否定句，and用於肯定句。
2) 但有時and 也可用於否定句。請注意其不同特點：
there is no air or water in the moon.
there is no air and no water on the moon.
在否定中並列結構用or 連線，但含有兩個否定詞的句子實際被看作是肯定結構，因此要用and。
典型例題
---i don't like chicken ___ fish.
---i don't like chicken, ___ i like fish very much.
a. and； and b. and； but c. or； but d. or；and
答案c。否定句中表並列用or, but 錶轉折。
判斷改錯：
(錯) we will die without air and water.
(錯) we can't live without air or water.
(對) we will die without air or water.
(對) we can't live without air and water.