In English, we use modal auxiliary verbs to express ideas such as possibility, ability, obligation and compulsion. It is often possible to use the same auxiliary to express different ideas. For example, we can use ‘can’ to talk about ability and possibility.
Test your understanding of modal auxiliary verbs with this grammar exercise.
Complete the following sentences using appropriate modal auxiliary verbs. The idea that you should express is indicated in the brackets.
1I ............... be there before 8 o'clock. (compulsion)
Wrong!
"Must" expresses compulsion or strong necessity.
2............... you lend me a few dollars? (polite request)
Select 2 answers.
Wrong!
"Would" and "Could" are polite ways to make this request.
3You ............... not have done this to me. (criticism)
Wrong!
"Should" forms "should not have" to criticize a past action.
4She ............... be driving now. (probability)
Wrong!
"Must" expresses a strong conclusion about what is probably happening now.
5It ............... rain in the evening. (weak possibility)
Wrong!
"Might" expresses a weak possibility.
6You ............... not have waited for them. (lack of necessity)
Wrong!
"Need" forms "need not have" to say that a past action was unnecessary.
7............... I wait any longer? (necessity)
Wrong!
"Need" asks whether something is necessary.
8Use the modal form followed by "to": You ............... follow traffic rules. (obligation)
Wrong!
"Ought to" is the modal form followed by "to" for obligation.
9............... I turn the heating on? (necessity)
Wrong!
"Need" asks whether an action is necessary.
10You ............... have helped me. Why did you just sit and watch? (criticism)
Select 2 answers.
Wrong!
"Should" and "could" can both criticize a past failure to help.
Answers
- I must be there before 8 o’clock. (compulsion)
- Would / Could you lend me a few dollars? (polite request)
- You should not have done this to me. (criticism)
- She must be driving now. (probability)
- It might rain in the evening. (weak possibility)
- You need not have waited for them. (lack of necessity)
- Need I wait any longer? (necessity)
- Use the modal form followed by “to”: You ought to follow traffic rules. (obligation)
- Need I turn the heating on? (necessity)
- You should / could have helped me. Why did you just sit and watch? (criticism)