2014-09-10 Structure: modals for certainty

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Homework: p. 56-59 exercises 1 and 2
ex 1
2 b ("should have" = it was a good idea, but you didn't do it)
3 b
4 a
5 a
6 a
7 b
8 b
9 b
10 b
You are not to do that. = You aren't supposed to do that.
"Should we go?" = is it a good idea to go, in general
"Shall we go?" = is it a good idea to go now? we're ready

"I could help you." = if you ask sometime, I could help
"I can help you." = I'm able to help you right now.
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ex 2
2 had to worry
3 supposed to do
4 were supposed to leave
5 Should we have left
6 don't have to leave
7 should you tip
8 you're supposed to do
9 Should you leave
10 ought to have given
11 could have left
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I had to leave early yesterday.
You were supposed to leave a tip.
I wasn't able to eat breakfast this morning.
(They were going to come, but they changed their mind.)
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p. 61 exercise 5 with a partner (find 8 more mistakes)
1 You're only supposed to take five
2 I figured I'd better take
3 I guess I ought to have expected something
4 I was embarrassed but I shouldn't have been
5 In China you shouldn't open gifts
6 She told me I had to go and try it on
7 Shall I bring you something...?
8 so I've got to sign off

subject + modal + base form (always)
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have to -> "hafta" (ONLY in pronunciation)
has to -> "hasta" (ONLY pronunciation)
got to -> "gotta" (sometimes in informal writing)
I've got to -> "I gotta"	"
'd better -> "better"		"
going to -> "gonna"		"
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Modals for speculation / guessing / conclusions:

The pottery must mean something.
= this is the only believable explanation
= I'd be very surprised if it's not true.

Irish monks may have arrived before the Vikings.
= this is one (of many) possible explanations
= I would not be surprised if it's true or if it's false.

He may be sick today.
He may not feel well today.
= these are possible explanations for why he isn't at school
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You could have called, but my phone was in the other room.
You might have called, but I'm not sure.
You  may  have called, but I didn't hear it ring.
= it is really possible that you called, but I don't know

You could have called. Why didn't you at least call?
You might have at least called me, you know.
= it was possible for you to call, but you didn't do it
  (and now I'm unhappy with you)
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Thiago couldn't have called. He was in Brazil at the time.
= it's not possible that he called
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He must not be at home. No one came to the door.
= usually he answers the door, he didn't, so he's probably not at home

He couldn't be at home. He left school only 5 minutes ago.
= it takes him at least 30 minutes to get home, so it's impossible that he's there already
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Homework: exercises 1 and 3
                 (74-75)(77-78)