"Tom and I is friends" 听着就别扭。两个人，动词必须用 are。主谓一致看着简单，坑不少。
基本规则
动词跟着真正的主语走，不是跟着紧挨着的名词：
- He likes apples. / They like apples.
and 连接：通常复数
两个名词用 and 连起来，动词用复数：Tom and I are friends. / Bread and milk are my breakfast.
两种例外用单数：指同一个人 The writer and teacher is coming；前面有 each/every 时 Every boy and every girl has a book.
就近原则
there be、either...or、neither...nor，动词跟着离它最近的主语走：
- There is a pen and two books.
- There are two books and a pen.
集体名词和特例
family、team、class 强调整体用单数，强调成员用复数：My family is big. / My family are watching TV.
people、police、clothes、trousers 永远复数：The police are coming.
口诀：and 连多数，each every 仍单数；there be 就近站，集体名词看意思。
