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Câu hỏi: Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the following questions.
You ____________ open the door before the train gets into the station.
It's very dangerous.
A. must
B. mustn't
C. should
D. don't have to
You ____________ open the door before the train gets into the station.
It's very dangerous.
A. must
B. mustn't
C. should
D. don't have to
Mustn't + bare infinitive: cấm làm việc gì
Don't have to do sth: it is unnecessary to do sth
Don't have to do sth: it is unnecessary to do sth
Đáp án B.