"You must go home and rest for a bit."

Translation: 你一定要回家休息一下。

[brandonrte]

Why is 要 necessary here?

[dafadllyn]

Because 一定 just means "definitely" and thus it intensifies 要 "to need, to must".

[GD-TO]

Yes, because 要 is being used here to form 'a command' (You must) - see https://www.chineseboost.com/grammar/five-uses-yao/

[Popsukka]

So if I say
'it must be fun... '
I can use just the 一定 but if there's a verb like in
'I must go now'
it requires 要 with it.
Is this correct? :)

[Alan946894]

2021.01.27
「一定」 functions as a adverb or you could think of it as an auxiliary, helper verb

You can even use 「一定」 with 「要」 as the Duo does here. In that case it may be easier to think of 「要」 as "to have to" and 「一定要」 as "must do" or "definitely have to". In fact 「一定」 can be used with most verbs

For example,
明天我有国语的测试、所以我要去学校
I have a Chinese test tomorrow, so I have to go to school

明天我有国语的测试、所以我一定要去学校
明天我有国语的测试、所以我一定去学校
I have a Chinese test tomorrow, so I [must\definitely have to] go to school

Even the Duo sentence here can be verbally split into 「要」、「一定」、or「一定要」回家 I believe

[Marcus534860]

So you CAN just have 你一定回家, with 回 serving as the verb that you 'must' (一定) do? Because Duo marks you wrong for missing the 要

[AlmzModa]

Yes please, I don't understand why you would have to add yao.

[GeoffreyHanson]

Shouldn't just 一定 or 要 also be accepted?

[NathanRasm]

2020-06-18 just 要 is accepted. But I think 你一定回家 is more like "you definitely go home" than "you ought to go home."

[Aleksandro_RU]

The same question

[Alan946894]

2020.8.26
一定 on its own doesn't function as a verb

[niche21stGmail]

Why 必须 is incorrect?

[LaBiciEsMia]

Why not "你一定要回家和休息一下" ?

[NathanRasm]

和 joins nouns together, but not verbs. You can, however, use the Chinese comma (，) to join the verbs.

[cSwede]

Same here

[Feather.55]

I have same question as brandonrte

[Eoin790683]

Still not fixed - 1 year on and it still insists on 要.

[_rika.]

要 needs to be there tho

[RobertChanger]

why is "要一定" incorrect?

[nolan374470]

Thoughts on 要 vs 需要 for this answer?

[wdtpw]

What's wrong with: 你需要回家休息一下 ?

[wdtpw]

what's wrong with 你应该回家休息一下 ?

[mendosi]

Because 應該 means 'should' but here we need something that means 'must'.

[wdtpw]

So I admit I'm a beginner, but here is where I get confused. If I see translations of it, eg here:

https://www.mdbg.net/chinese/dictionary?page=worddict&wdqb=應該&wdrst=1

Then, "must" comes up as one of the options. It also gives must as a translation in this duolingo word list:

https://duolingo-mandarin-chinese.netlify.app/#166

No doubt you're right. I just feel duolingo is very much not clear at times.