UNIT 9 Lesson 1

Modals can, shoud, could: meaning
Use can to express ability or possibility.
Use could to suggest an alternative or to make a weak suggestion.
Use should to give advice or to express criticism.

Modals: form
Modals are followed by the base form of the main verb of the sentence, except in short answers to questions.
Never add -s to the third-person singular form of modals.
Never use to between modals and the base form.
Use not between the modal and the base form.

Modals: questions
In yes / no questions, the modal comes before the subject. In information questions, the question word precedes the modal.

A.- complete each sentence or question:
1.- Who should buy the tickets?
use rule # 6  never use to between modals and the base form.
2.- Where can I find a hotel?
use rule # 9 yes/ no question.
3.- You could walk or take the bus.
use rule # 6 and 4 never use to between modals and the base form. and  modals are followed by the base from of the main verb of the sentence, except in short answers to questions.
4.- should I call you when I arrive?
use rule # 8 in yes/no questions, the modal comes before the subject. in information questions, the question word precedes the modal.
5.- We can´t take the bus; it left five minutes ago.
use rule # 6 never use to between modals and the base form.
6.- When should you give the agent your boarding pass?
use rule # 4  modals are followed by the base from of the main verb of the sentence, except in short answers to questions.
7.- Which trains can get me there before dinnertime?
use rule # 4modals are followed by the base from of the main verb of the sentence, except in short answers to questions.