4, They had to cook dinner on their own.
5, Lan wasn’t helped to fix her dress yesterday.
6, Sara, was this poem written on your own?
7, Nam wasn’t helped to clean his bicycle.
8, I’m learning to play the flute by myself.
9, Nobody paid the meal for him.
10, Paul copies his friend’s homework instead of doing it on his own.
11, Tuan doesn’t need water that tree every day.
12, You must not make noise in the library.
13, Does he have to leave now?
14, You do not need to go to school early.
15, You ought to keep the house clean and tidy.
16, Students ought not to make noise in class.
17, You should not put so much salt in the soup.
18, Because I want to work as an interpreter in the future, I am studying Russian at university.
19, Because these objects are very dangerous, we must put them in locked cupboards.
