The document discusses the use of the word "must" to make logical conclusions and guesses based on available information. It can indicate a strong guess, as when one assumes someone is sleepy based on seeing them yawn. "Must" can also express necessity, as when a ticket is needed to enter a movie theater. Similarly, "must not" can mean a strong negative guess, as guessing someone dislikes pickles after leaving them on the plate, or it can indicate prohibition, as when swimming is forbidden near sharks.

1. 7-11MakingLogicalConclusions:
Must
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2. Thespeakerismakinga
logicalguess:Shebases
herguessonthe
informationthatNancy
isyawning.
Her strong guess is that Nancy is
sleepy. She uses must to express his
logical conclusion.
Nancy is yawning.
She must be sleepy.

3. Comparethetwo
meaningsofmust:
Strong guess Necessity
Amy plays tennis
every day. She
must like to play
tennis.
If you want to get
into the movie
theater, you must
buy a ticket.

4. Comparethetwo
meaningsofmust
not:
Strong negative
guess
Prohibition
Eric ate
everything on his
plate except his
pickle. He must
not like pickles.
There are sharks
in the ocean near
our hotel. We
must not go
swimming there.