Modals with “Not” 1 - Must not, Do not have to

Which is best: don't have to or mustn't ?

You ________ smoke in a gas station.
1. don't have to
2. mustn't
You ________ pass a test to ride a bicycle.
1. don't have to
2. mustn't
You ________ unplug the computer while it is turned on.
1. don't have to
2. mustn't
Shops ________ sell cigarettes to children.
1. don't have to
2. mustn't
This bus is free! You ________ buy a ticket.
1. don't have to
2. mustn't
You ________ live in Canada to study at the University of Victoria. You can take a course by Internet.
1. don't have to
2. mustn't
In Canada, employers ________ discriminate against women or minorities. It's against the law.
1. don't have to
2. mustn't
You ________ buy the text book for this course -- you can borrow mine.
1. don't have to
2. mustn't
Canadians ________ get a visa to travel to the US.
1. don't have to
2. mustn't
You ________ be late for class, or the teacher will be angry.
1. don't have to
2. mustn't