有两种情况：
1.当描述物品时.
一个物品用IS，多数物品用ARE。
例如：The bag is dirty.
The bags are dirty.
2.当描述人称时.
第一人称I后接am,第二人称you后接are,第三人称he/she 后接is，表复数的they后接are.
例如：1.I'm a good student.
2.You are a good example for
other students.
3.He is such a good man that
everybody likes him very much.
4.They are the volunteers of
Olypic Games.
5.People are ignorant at that
old time,they strong believe
there is god in the world.
注意：people后面只能接are,不能接is。
温馨提示：答案为网友推荐，仅供参考