2014-10-21 Structure: modals for obligation

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http://www.pastebin.com/u/gmalivuk
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MODALS
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should	shall
might	may
could	can
would	will
must
ought to
had better
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have to (similar to "must")
be able to (similar to "can"/"could")
be supposed to (similar to "should")
be to (similar to "should" or "must")
be going to (similar to "will")
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modals don't change for he/she/it
modals are always followed by a verb in the base form
modals don't change tense (except e.g. can->could)
modals must be the first verb in a verb phrase (= only one)

modals are auxiliary (helping) verbs, along with:
"have" for perfect tenses
"be" for progressive and passive constructions
"do" for simple present and past
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hors d'oeuvres ("orderve"): the small food items that might be available while socializing before a larger meal

bargain/haggle: negotiate over the price of something

7% tax + 18% tip = 25% addition
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You must pay the tax. (100% obligation, no choice)
= You have to pay the tax. = You've got to pay the tax.
You must not drive without a license. (sometimes "can't")
I had to go to the doctor yesterday. (and I went there)

You had better study. (if you don't, you'll fail tomorrow)
You had better not leave  your book at home. (if you do->bad)
You'd better have studied.
 = I hope you studied, because if you didn't, you'll fail.

You should study. (in general; it will give you better grades)
 = studying is the best option to choose
You shouldn't speak Arabic in class.
 = it is not a good idea to speak Arabic
(ought to = should for affirmative sentences, not common in questions and negative sentences)
You should have studied. (but you didn't, so you failed)
You shouldn't have stayed up so late. (now you're tired)
 = it was/wasn't a good idea, but you did the opposite

You're supposed to arrive at 9:00. (expected by the teacher)
It's not supposed to rain today. (expected by meteorologists)
"be supposed to" = "be expected to" by authority or experts
You are to arrive at 9. (If a person is expected to do some action, we can omit "supposed".)
The movie was supposed to start at 7. (but it didn't)
You weren't to find out until later. (but you did)

might/could = one possibility out of many
might have / could have = it was possible (but didn't happen)

don't have to = no obligation, you can do what you want
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Homework: p. 56-59, exercises 1 and 2