5. There’s a Subtle Difference Between Must and Have To

　　Must 与Have To有细微的差别

　　Modal verbs in English serve to indicate possibility, obligation and more. The most common examples of modal verbs include can, may, must, will and shall. Must is the one indicating an obligation or a necessity to do something.

　　英语中的情态动词用来说明可能性，义务或者其他。最常见的情态动词包括can, may, must, will和shall。Must是用来说明义务以及做某事的必要性。

　　I must wake up early to catch a morning train.

　　我必须早点起来去赶早车。

　　However, we could also say:

　　然而，我们也可以说：

　　I have to wake up early to catch a morning train.

　　我不得不早点起来去赶早车。

　　语法上来说，他们都对，但是有什么细微的区别吗?有!

　　The difference between must and have to is subtle. Both refer to an obligation, but must indicates an opinion or suggestion. Have to is an expression of a more objective obligation coming from an outside force.

　　Must与have to之间的差别是细微的。两者都指义务，但是must是指意见或者建议。Have to指来自于外部世界的客观义务。

　　因此说某个人必须做她的家庭作业是你的意见。说她不得不做她的家庭作业代表着她必须这样做。在非正式的场合must和have to不可互换。在正式一点的场合，熟知must和have to的区别你就可以把它们区分开。

　　6. Always Check for Subject and Verb Agreement

　　时常检查主谓是否一致

　　One of the most basic grammar rules in English states that the subject of the sentence has to agree with its verb. To approach fluency in English, it’s crucial to understand subject-verb agreement. The subject of a sentence can be either singular or plural, which will determine what form the verb takes.

　　英语中最基本的语法规则就是句子的主语必须要和谓语一致。为了流利地使用英语，了解主谓一致是至关重要的。句子的主语可以是单数也可以是复数，主语的单复数形式决定了它的谓语要采取何种形式。

　　For example:

　　例如：

　　She likes pizza.

　　她喜欢披萨。

　　They like burgers.

　　他们喜欢披萨。

　　But what happens when a sentence gets more complicated?

　　但是如果一个句子更加复杂该怎么办呢

　　When there’s more than one subject connected by and, it’s a compound subject that requires a plural.

　　当句子中存在由and连接的并列主语时，那么这就是一个复合主语，谓语动词需要用复数。

　　Lily and Tom want to order pizza. (They want to order pizza.)

　　莉莉和汤姆想要点披萨。(他们想要点披萨。)

　　But here’s where things get really complicated. Sometimes the subject is accompanied by an additional piece of information that follows along with, together with, as well as, such as and more. These don’t change the subject into a compound subject and don’t require a plural verb.

　　但是这里我们要说明的才是真正复杂的。有时，主语后会伴随额外的信息，由along with, together with, as well as, such as 或者其他的词连接。这种情况下不需要把主语看成是复合主语，谓语动词也不需要是用复数形式。

　　Lily, just like Tom, wants to order pizza. (She wants to order pizza. So does Tom.)

　　莉莉想要点一份披萨，汤姆也是。

　　I, together with Matthew, am going for a walk. (I am going for a walk. Matthew is going with me.)

　　我要去散步，马修和我一起。

　　Note that this a slightly awkward sentence, and using a compound subject like Matthew and I would be preferable here.

　　注意这个句子有一点歧义，使用复合宾语Matthew and I 会好一些。

　　A book, along with a few cards and pencils, was on the table. (A book was on the table. There were also a few cards and pencils.)

　　书在桌子上，桌子上还有一些卡片和铅笔。

　　Notice how these sentence elements provide additional information that can be safely removed. The sentence would be less informative, but still grammatically correct.

　　注意句子中提到的一些附加信息可以被移除。虽然这样句子可能不那么富有信息性，但是语法是却是正确的。

　　A simple way to check for subject and verb agreement is to replace the subject with an appropriate pronoun, like we did in the first sentence above.

　　这里有一个验证主谓是否一致的简单方法，可以用一个合适的代词来替换主语，就像我们在第一个句子里做的一样。

　　Lily, just like Tom, wants to order pizza. (She wants to order pizza.)

　　莉莉想要点一份披萨，汤姆也是。(她想要一份披萨。)

　　Lily and Tom want to order pizza. (They want to order pizza.)

　　莉莉和汤姆想要点一份披萨。(他们想要点一份披萨。)

　　If the sentence still makes sense, your subject and your verb are in agreement!

　　这样做，如果句子仍旧有意义，那么你所使用的主语和谓语就是一致的。