Put the verb in parentheses in the correct form: verb base, progressive infinitive or perfect infinitive. Each option will be used only once for each set of sentences. Then determine whether the modal sentences illustrate epistemic or non-epistemic modality, and whether they communicate possibility or necessity.

1. a. You should(prepare) for tomorrow’s exam.

b. You should (put) your computer in a safer place when you’re away from home.

c. You should(back up) that important document. It’s too late now.

2. a. The computer should (have) a full charge. It’s been plugged in for a while.

b. They should (arrive) by now – maybe they’ve been held up.

c. They should (arrive) soon if indeed they left on time.

3. a. Swimmers must (finish) within the top 16 in their event to go to regionals.

b. We all must (work) when the boss walks in. Otherwise, she’ll accuse us of laziness.

c. You must (be) 18 years old to participate in this study.

4. a. John isn’t home yet. He must (work) late tonight.

b. They must (finish) by now. They’ve been working for hours.

c. She’s starting university soon, so she must (be) about 18.

5. a. The bus driver didn’t stop. He must not (see) us.

b. Rude wait staff must not (realize) that bad service means no tip.

c. Ben is not in his office. He must not (work) today.

6. a. Marie is unhappy at work. She might (quit) her job.

b. She never got the package I sent. I might (send) it to the wrong address.

c. Where’s Sarah? – I don’t know. She might (sleep).