V. Choose the appropriate modal verb.
1. John _____ go to the dentist because he had a toothache.
a) must b) should c) had to
2. You _______ stay in the foreign country longer than your visa allows.
a) needn't b) mustn't c) shouldn't
3. We ________ help our granny to do the housework.
a) should b) may c) are able to
4. At the airport your luggage ______ be lost.
a) must b) can c) should
5. You ________ talk aloud in the reading-hall.
a) can't b) mustn't c) needn't
6. Cats _______ see very well in the dark.
a) should b) have to c) can