Subject-verb agreement is a fundamental grammar rule in English. It means that the verb in a sentence must match the subject in both person and number. This ensures that sentences are grammatically correct and clearly structured.
Person and number are the two key components of subject-verb agreement. Person refers to who is speaking: first person like I or we, second person which is you, and third person such as he, she, it, or they. Number simply refers to quantity - whether we're talking about one thing, which is singular, or more than one thing, which is plural.
Now let's look at the specific rules for subject-verb agreement. The most important rule is that third person singular subjects require verbs to add -s or -es, like 'He runs' or 'She watches'. The verb 'be' changes form based on the subject: I am, you are, he is, we are, they are. For most other verbs, they stay the same except for third person singular. For example, 'I walk' is correct, 'He walks' is correct, but 'He walk' is incorrect.
The purpose of subject-verb agreement is to ensure grammatical correctness and clear communication. When we follow these rules, our sentences become clear and understandable, following standard English conventions. Proper subject-verb agreement improves communication effectiveness and demonstrates good language skills. Without it, sentences can become confusing and difficult to understand.
主谓一致是英语语法中的一项基本规则。它要求句子中的动词必须与主语在人称和数上保持一致。例如，当主语是第三人称单数时，动词也要使用第三人称单数形式。这个规则看似简单，但在实际应用中需要注意许多细节。
让我们看看主谓一致的具体规则。第一人称单数I和复数we使用动词原形。第二人称you无论单复数都用原形。第三人称单数he、she、it需要在动词后加s或es，而第三人称复数they使用原形。这个表格清楚地展示了不同人称和数与动词形式的对应关系。
第三人称单数的动词变化有规律可循。一般情况下直接加s，如work变works。以s、x、ch、sh结尾的动词加es，如watch变watches。以辅音字母加y结尾的动词，要把y变成i再加es，如study变studies。还有一些特殊变化需要记住，如have变has，be变is。
be动词是最常用的系动词，它的主谓一致规则需要特别注意。I总是搭配am，第三人称单数he、she、it搭配is，而you无论单复数以及所有复数主语都搭配are。记住这个口诀：我用am，你用are，is跟着他她它，复数全部都用are。
总结一下，主谓一致是英语语法中的基本规则，要求动词必须与主语在人称和数上保持一致。记住第三人称单数主语需要动词加s或es结尾，be动词根据主语选择am、is或are的形式。掌握主谓一致规则对于书写和口语表达清晰、语法正确的英语至关重要。