Complete the following sentences using an appropriate auxiliary verb form.
1You have been riding non-stop for hours. You ............... be very tired.
Wrong!
Use "must" for a strong present deduction based on clear evidence.
2She looks much older than her brother. She ............... be about forty.
Wrong!
Use "must" for a strong deduction about the present.
3I know I left my phone on this table, and it is not here now. Somebody ............... it.
Wrong!
Use "must have taken" for a strong deduction about a past action.
4That ............... be true. She would never do something like that.
Wrong!
Use "can't" to say that something is impossible or very unlikely.
5You ............... him a fool. It really upset him.
Wrong!
Use "shouldn't have called" to criticize a past action.
6The doctor said I ............... give up smoking.
Wrong!
Use "must" to report a strong obligation or order.
7You ............... nicer to her. She really cares for you.
Wrong!
Use "should have been" to express criticism or regret about past behavior.
8............... you mind standing up for a moment?
Wrong!
Use "Would" in the polite request "Would you mind...?"
9That was a dangerous place to go hiking. You ............... your back.
Wrong!
Use "could have broken" for something bad that was possible but did not happen.
10"Who is at the door?" "I'm not sure. It ............... be the postman."
Wrong!
Use "could" when an answer is possible but not certain. "I'm not sure" rules out "must", and "can" is not used for a possibility about a specific present situation.
Exercise complete
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correct answers
Answers
- You have been riding non-stop for hours. You must be very tired.
- She looks much older than her brother. She must be about forty.
- I know I left my phone on this table, and it is not here now. Somebody must have taken it.
- That can’t be true. She would never do something like that.
- You shouldn’t have called him a fool. It really upset him.
- The doctor said I must give up smoking.
- You should have been nicer to her. She really cares for you.
- Would you mind standing up for a moment?
- That was a dangerous place to go hiking. You could have broken your back.
- “Who is at the door?” “I’m not sure. It could be the postman.”