Есть несколько вариантов :
1.Им лень
2.Нет возможности
3.Считают это ненужным
Scissors, trousers, scales, tongs, goods, clothes, riches, news, people, money, - во множественном
She must do her homework.
They must visit their grandmother.
I must help my Mum.
We must cook a cake.
He must bye a car.
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I mustn't go to walk with my dog.
They mustn't eat meat.
She mustn't live without their parents.
John mustn't sleep so late.
I mustn't stay at home one.
I did my homework yesterday evening. I love to draw buildings. My father and I dug a hole in thethe ground. I felt disappointed when I heard the news. My sister was very careless and fell down. He forgot about his household chores.
This is my a cat
my a cat can jamp
my a cat can not real
I can run.my a cat
I can not climb.my a cat