Exercise 4: Điền vào mỗi chỗ trống sau bằng một động từ khuyết thiếu đã học. 1. I left my bike here and now it's gone. Someone have borrowed it. 2. "The door was open." "It_ have been open. I had looked it myself and the key was in my pocket." 3. I want this letter typed, but you do it today. Tomorrow you will do. 4. We forget to shut the gates. 5. If you go to a dentist with a private practice, you pay him quite a lot of money. 6. You talk to other candidates during the exam. 7. "Have you seen John?" "No. But he be studying in the library". 8. As I won't be at home tonight, I do my homework during my lunch break. 9. Passengers smoke until the signs have been switched off. 10. There are a lot of tickets left, so you pay for the tickets in advance. 11. I have worn my best suit to the party yesterday; everyone else was very casually dressed. go on a picnic with my 12. "What are you doing this weekend?" "I haven't decided yet. I family." I do it now. 13. Can you repair my bicycle? -Oh, yes, 14. It's a secret. You _let anyone know about it. 15. I'm not sure. I come a few minutes late. 16. Secondary school students nowadays_ 17. I had read the book last night before I went to bed. 1 never took it out of this room. It wear uniform. be lying around here somewhere. Where it be? 18. When you have a small child in the house, you_ leave small objects lying around. Such objects be swallowed, causing serious injury or even death. take your umbrella along with you today. It rain later on this afternoon. 19. You take a taxi if I want to be on time. 20. I be at the meeting by 10 pm I will probably

might/must

can't

needn't

musn't

have to

mustn't

might 
have to 
mustn't
needn't
needn't
might 
will 
mustn't
might 
have to 
must / can 
shouldn't - might 
should take - might rain
must - have to

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