and的用法的主谓一致

用"and" 连接的主要到底是单数还是复数, and连接的并列结构作主语，可根据主语的意义决定谓语动词的单、复数形式。

1. 复合主语用"and"连接, 表示一个整体, 是单数:(并列主语如果指的是同一个人、同一事物或同一概念时，谓语动词用单数形式)

The secretary and treasurer has filed the minutes. (The secretary and treasurer is one person)

2. 如果每部分都有each 和every来限制, 是单数:

Each player and every team receives a prize.

3. 除了上述情况, 用"and"连接都是复数:

Rain and snow were falling at the same time.

There are one book and two magazines on the table.

The computer and the printer are compatible.

The boys and their father are going together.

Now,你的例句中的"bread and butter" 是个特殊的词组, 已经形成固定词组, 多数情况是做为一个整体, 也就是说是单数:

Bread and butter is eaten everyday.

但是, 也可以说:

Bread and butter are eaten everyday. 这里重点放在"bread" 和"butter"两种食物上.

你的这个例句还有一个clue, 就是宾语是food, 是个单数.

4.主语由连词or,either...or,neither...nor,not only...but(also)等连接的两个名词或代词组成时，其谓语动词应与最近的名词一致。例如：

Either you or I am wrong.

Not only his friends,but also he himself is looking forward to the holding of the party.