Is it because modal verbs don't change their form, but " have to" does?

是不是因动词不改变自身形式，但是 “have to” 会改变？

We also have modal auxiliary verbs, commonly called modals or modal verbs.

我们也有助动词，通常称动词。

When making suggestions, modal verbs can be very useful.

做建议时动词非常有用。

So you already know I'm sure about superlatives and modals of necessity.

你已经道「最高级」和「动词」的重要性。

Can is a modal verb with many uses.

Can 是一个有许多用法的动词。

But why is " have to" different from other modal verbs?

但是什么 “have to” 和其动词不一样呢？

I tried to teach something about modal verbs.

我试着们一些关于动词的内容。

Look for modal verbs like 'could', 'might' or 'must'.

寻找像“可能”、“也许”或者“一定”这种动词。

We often use the words 'maybe' and 'perhaps' without a modal to express uncertainty.

我们经常用maybe和perhaps而不是动词表达不确定性。

You were right to question the use of two modal verbs together.

你对两个动词的用法提出质疑是对的。

But again, " maybe" is an adverb, not a modal.

但是，" maybe" 是一个副词，不是词。

For this usage, the word " may" is a modal verb.

在这种用法中，单词" may" 是动词。

We'll start using more phrasal verbs, modal verbs, contractions, some idioms.

我们会开始测试更多的短语动词、动词、缩写，还有一些习语。

You may remember that the verb " should" is a modal verb.

你可能还记得动词" should" 是动词。

The modal verb needs to be in the question tag!

动词需要出现在反义疑问中。

These days we are more likely to use modal verbs such as 'should' or 'would'.

现在我们更多的时候是用动词should和would。

Why don't we cover the modal " WOULD" to make requests?

我们什么不谈谈动词 WOULD 用做表示请求的用法呢？

No, why? Because that's a modal verb.

不用，什么？因有个动词。

But let's use " should" , that's our modal verb, before the subject.

但让我们在主语前用动词 should。

Modals are added to another verb to show capability or possibility or necessity as well.

动词被添加到另一个动词前面来表示能力或可能性或必要性。