Теория:

Study some information about negative sentences and questions with 'must'.
 
Для построения отрицательного предложения с must необходимо использовать следующий порядок слов:
subject \(+\) must \(+\) not \(+\) Verb in the \(1\)st form (without 'to') \(+\) other parts of the sentence.
Также можно использовать сокращение отрицательной формы:
 
must not \(=\) mustn't.
  
You mustn't (must not) take this mobile phone. It's not yours.
  
glasses-1052023_640.png
Рис. \(1\). Mobile phone  
 
Для построения общего и специального вопросов используйте следующие структуры.
  
General question
Must \(+\) subject \(+\) Verb in the \(1\)st form (without 'to') \(+\) other parts of the sentence?
Special question
Question word (when, how, what....) \(+\) must \(+\) subject \(+\) Verb in the \(1\)st form (without 'to') \(+\) other parts of the sentence?
Must I help in the garden?
  
What must she read now?
  
girl-1423501_640.png
Рис. \(2\). Reading
Источники:
Рис. 1. Mobile phone, 2015, https://pixabay.com/images/id-1052023/ Pixabay License CC0 Free for commercial use No attribution required
Рис. 2. Reading, 2015, https://pixabay.com/images/id-1423501/Pixabay License CC0 Free for commercial use No attribution required