2015-11-13 Grammar: modals for inference

Greg Malivuk
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http://www.pastebin.com/u/gmalivuk
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Homework: think of an answer for the third mystery. (The police officer is the boy’s mother.)
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p. 261 - modals for logical inference
(You must sign in before you use the elevator. = This is your only option.)
The police officer must be his mother. = This is the only believable explanation.

(You should do your homework. = This is the best option (but not the only one).)
He should be home by now. = This is the best explanation (but not the only one).

(You could take a bus. = This is one of many options.)
She could be sick today. = This is one of many explanations.
= She might be sick today. = She may be sick today.

She may not feel well. = She might not feel well. = “She doesn’t feel well” is one of many explanations.

(You shouldn’t stay up so late. = This is not the best option.)
The food shouldn’t be too hot now. = It’s probably not too hot. (“too hot” is not the best explanation)

(You must not use your phone in class. = This is not an option.)
The man must not be tall enough. = “He is tall” is not a believable explanation.

(I can’t speak Arabic. = I don’t have this ability. It is impossible.)
The officer couldn’t be the boy’s father. = This is not a possible explanation.
= The officer can’t be the boy’s father.
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p. 262 exercise 5
1 a might/could/may/should
  b could/may/might
  c may/could/might
2 a couldn’t/can’t
  b shouldn’t
  c can’t/couldn’t
  d must
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“should” and “shouldn’t” are most common with prediction-like inferences--there’s some evidence in the past that makes me think this is probably true or probably false.
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Homework: read p. 264 (inferences about the past), do p. 265 exercise 8