Subject-predicate agreement means that the predicate verb and the subject are consistent in person and number. Subject-predicate agreement must follow three principles: grammatical agreement, meaning agreement and proximity agreement.

1. Grammatical consistency principle: the subject is singular, the predicate verb is singular, the subject is plural and the predicate is plural. For example:

Tom is a good student.

Tom is a good student.

They often play football on the playground.

They often play football on the playground.

2. Consistent meaning: it means that the subject is singular in form, but the meaning is plural, so the predicate verb is plural; Or the subject is plural in form but singular, which is the singular form of the predicate verb. For example:

My family is having lunch.

Our family is having lunch now.

Twenty dollars is too expensive for this book.

Twenty dollars is too expensive for this book.

3. Proximity agreement: refers to whether the predicate verb is singular or plural, depending on the subject closest to it. For example:

Not only the teacher but also his students like playing football.

Not only the teacher but also his students like playing football.

There is a pen and some books on the desk.

There is a pen and some books on the desk.