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

是不是因为情态动词不自身形式，但是 “have to” 会？

When making suggestions, modal verbs can be very useful.

做建议时情态动词非常有用。

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

你已经知道「最高级」和「情态动词」重要性。

Can is a modal verb with many uses.

Can 是一个有许用法情态动词。

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

但是为什么 “have to” 和其他情态动词不一样呢？

I tried to teach something about modal verbs.

我试着教了他们一些关于情态动词。

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

寻找像“可能”、“也许”或者“一定”这种情态动词。

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

我们经常用maybe和perhaps而不是情态动词表达不确定性。

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

你对两个情态动词用法提出质疑是对。

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

但是，" maybe" 是一个副词，不是情态词。

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

在这种用法中，单词" may" 是情态动词。

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

我们会开始测试更短语动词、情态动词、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" 是情态动词。

The modal verb needs to be in the question tag!

情态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'.

现在我们更时候是用情态动词should和would。

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

我们为什么不谈谈情态动词 WOULD 用做表示请求用法呢？

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

不用，为什么？因为有个情态动词。

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

但让我们在主语前用情态动词 should。

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

情态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。

Now it's important to consider modals, when it comes to the first conditional.

当说到第一类条件句时，考虑情态动词很重要。