E04
core
Speaker stance
Modality
Obligation Aura
Must it happen? Is it required?
basic
Modal verb
Deontic modality
Obligation
含义
A modal layer expressing necessity, duty, rule, requirement, pressure, or unavoidable need.
如何识别
Ask whether someone has to do something.
示例
单词
must|have to|need to|required
短语
must leave|have to work|need to study
句子
You have to finish this today.
Visual guide
Basic shape
Obligation layer:
[person] → [event]
↑
rule / duty / need
must / have to / need to
You have to finish this today.
Compare shape
Same force, many shapes: EN modal: must leave EN phrase: have to work Verb: need to study Impersonal: required Particle/suffix: WORK + OBLIG
语言视角
用母语深入讲解
中文
显性程度
strong
重要程度
Obligation uses 要, 必须, 应该, 得, and related modal expressions with different strength and register.
我必须走了。
wǒ bìxū zǒu le = I must leave LE
在所学语言中
英语
显性程度
strong
学习难度
英语用 must、have to、need to、should、be supposed to 等表达义务或必要性。must 通常更强，should 更像建议或应当，have to 常表示外部要求。
You must wear a seatbelt.
must + wear：must 表示义务或要求，意思是“你必须系安全带”。
常见易错点
学习者常混淆 must、have to、should 和 need to，可能把语气说得过强或过弱。
Same block, different coding
Both languages use this block strongly, but they signal it differently. Focus on form changes, not only meaning.