Fill in the blank with the correct modal.
Tom is not in his room, and his gardening gloves are missing. I am sure he ________ be working in the garden.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → must
Complete sentence: Tom is not in his room, and his gardening gloves are missing. I am sure he must be working in the garden. From these two facts the speaker says “I am sure”.
| Option | Meaning and use | Example |
|---|---|---|
| (1) might | only a small chance. It does not go with “I am sure”. | Take an umbrella, it might rain later. |
| (2) need | as a modal, used in negative sentences and questions. It cannot fill this positive sentence. | You need not bring lunch tomorrow. |
| (3) should | what we expect or what is right to do. It is weaker than being sure, and the speaker is sure. | The bus left at nine, so it should reach Agra by noon. |
| (4) must (answer) | a sure guess about something because of what we can see | The lights are off and the gate is locked, so they must be out. |