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hi everybody my name is Alisha today I'm
going to talk about the words must and
must not and how we use them to talk
about possibility in this lesson I'm
going to talk about a present
possibility so possibility now and I'm
going to talk about a possibility in the
past too so with this lesson I want to
introduce a few common patterns and some
example sentences to show you the
meanings of must and must not for
present and past and also just to give
you maybe some tools so that you can use
these grammar points to talk about
possibility in your life as well so
let's get started okay first I want to
talk about present possibility the
present possibility so these are things
we want to talk about now we think are
possible now the first group of examples
the first group of patterns I want to
look at is must be plus a noun phrase
must be plus an adjective or must be
plus the verb in the ing form these are
a few examples of some patterns we can
use with must to talk about possibility
now possibility in the present a couple
points though we use must and must not
as well to make guesses we're making a
guess about something we don't know in
other words so there's some information
we do not have we're making a guess when
we use must the nuance of must is that
there's a very high chance something is
correct
so very high meaning near 100% a very
high chance the guess is correct also
keep in mind that because this is a
guess because you are kind of giving an
idea or giving a very strong opinion
that something is probably correct it's
very strange to use must and must not
for that matter it's very strange to use
them in most cases to talk about
yourself because
we know ourselves and we know our group
so in a few exceptions in a few special
cases we can use must and must not to
talk about ourselves but I'll talk about
that later just keep in mind that in
many cases it is strange to use must and
must not to talk about yourself because
you know yourself in most cases so let's
take a look at a few examples of how to
use these first let's look at the first
group the first pattern here must be
plus a noun phrase so if we use must be
plus a noun phrase it talks about an
expression that is that has a high
chance something that has a high chance
of being true and it's related to a noun
phrase so for example the expression
this must be the right house meaning
there's a very very high near 100%
chance that this house is the correct
house this in other words this is the
house I'm looking for there's a very
high chance of that one more example she
must be a student here I've used student
as my noun phrase so in this situation
maybe I'm looking at a person and I
guess based on her appearance oh she
must be a student there's a high
possibility she's a student these are a
few examples of how to use must be with
a noun phrase let's look at another
pattern the second pattern is must be
plus an adjective so just as we did with
noun phrases we use must be plus an
adjective so for example you must be
tired looking at another person you can
guess they must be tired there's a very
high chance that person is tired based
on their appearance or some other hints
you get from them tired is our adjective
here another one they must be angry they
must be angry so again looking at a
group of people or a couple of people
based on the appearance based on the
situation you guess there's probably a
high chance those people are angry they
must be angry alright one more pattern I
talked about using must be plus a verb
in the ing form so here
we see again must be but in this case we
have the ing form of a verb here so in
this example sentence the computer must
be thinking must be thinking thinking is
a word we use to talk about like
functioning or moving or working doing
its job in other words but for computers
we like to sometimes say the computer is
thinking the computer is processing here
a computer maybe is taking a long time
the computer must be thinking there's a
high chance the computer is working is
thinking one more he must be working he
must be working maybe if you send your
friend a message and there's not a
response in a timely fashion the
response is very slow you could say to
make a guess oh he must be working
that's why he hasn't responded she must
be working there's a high chance that at
this point in time at this point now
that person is doing something in this
case working ok let's take a look now at
the negative examples of this grammar
point so must not plus the same points
we just talked about must not plus a
noun phrase must not plus an adjective
and must not plus a verb in the ing form
so we'll use exactly the same pattern
and we can even use in many cases
similar noun phrases and similar
adjectives but it's important to
remember must not expresses extremely
low possibilities so in extremely low
possibility meaning very near to zero if
not impossible so the nuance here is
it's impossible or there's like a 0.001
percent chance
very very low possibility so please keep
this in mind must be or must is used to
make a high high possibility guests must
not however expresses very low
possibility very low so let's look at a
few examples similar to the other
examples we looked at
with a noun phrase this must not be
again must not be the right house so it
is impossible that this house is the
correct house in other words here she
must not be a student here hi
she is a student here low chance she is
a student impossible she is a student
next one with adjectives here he must
not be busy in this case he must not be
busy is my adjective low chance he is
busy very low chance he is busy they
must not be happy they must not be happy
is a very low chance that they are happy
so again these are all guesses based on
some outside information like a visual
or some other hints you have your making
a guess in this case a very low chance
of something to move on to the final
powder she must not be studying so at
this point in time there's a very low
chance she is studying very low chance
she must not be studying one more they
must not be travelling here so again low
chance that these people in the sentence
are travelling so please just keep in
mind positive statements Express high
possibility negative statements Express
low possibility or near impossibility
okay now let's take a look let's move
from present possibility to past
possibility this gets a little bit more
complicated or a little bit more
challenging maybe but we can keep many
of the same patterns really when we want
to talk about past possibility we need
to use a pattern like must have been so
you can see in present possibility we
use must be in past possibility for a
positive sentence anyway we use must
have bin must have been this is a
grammar change so please be careful but
we can use noun phrases adjectives and
the same verb in the ing form just as we
did with present possibility this is
true for the for positive statements
here and for negative statements again
we update negative statements with must
not have been in the past so let's take
a look again we're looking at very high
chances with the positive however there
in the past these are very high chance
situations very high chance of guesses
in the past
in this case and as we talked about in
the present possibility section with not
must not have been this expresses
impossibility in the past impossibility
very very low chance so let's look at a
few examples here to four positive
statements that must have been the right
house in the past
ah that must have been the right house
for example you drive past the correct
place you can remark oh that must have
been the right house another one he must
have been the waiter he must have been
the waiter maybe I made a mistake
Oh he must have been the waiter for
example with an adjective the computer
must have been broken the computer must
have been broken that's why it wasn't
working for example or you must have
been tired you must have been tired
after your trip for example so again
making a very high-level possibility
guest in the past here with the verb
form in the ING she must have been
studying she must have been studying for
example last night or this morning he
must have been working as well so you
can see I've just updated some of these
to show how we changed the sentence from
the past to the present and vice-versa
let's look at some negative examples
that must not have been the office that
must not have been the office so in
other words there was a mistake a low
chance that that building was the office
another example you must not have heard
the news you must not have heard the
news there's a very low chance you heard
the news so here must not expresses that
very low chance okay just a couple more
patterns I want to talk about over here
I have must have plus a verb and must
not have plus over so these are a couple
of different patterns we can use in the
past but we use a verb with them instead
of using a noun phrase and adjectives
and so on as we've talked about here we
use just a regular verb in the past
tense here but again in the positive
form positive form expresses a
by chance of something high-level
possibility of something low chance for
the negative form as well so
impossibility so let's take a look then
at how we use a verb after must and must
have in the past so we must have made a
mistake this is one of those cases where
where we using we or using yourself as
the subject of a sentence is actually
okay because you're talking about
yourself in the past and something that
is different between now and the past so
in this case you learn some new
information and you make a guess about
your past self in this case I made a
mistake but in the past give given new
information you can guess oh we must
have made a mistake I must have made a
mistake I didn't know it at the time in
this case we use we he must have made a
mistake so here's the past participle
form of the verb must have made a
mistake or they must have gone to
somewhere else or they must have
whatever we can use we can use the past
participle form of the verb here to show
a a past activity a past possibility
situation let's look at one more example
then so my package must have shipped my
package must have shipped so in this
case the package there's a high
possibility my package was sent from a
warehouse for example or from a company
so there's a high level of possibility
here my package must have shipped that
past participle form of the verb okay
let's look however at the negative form
the negative form he must not have come
to work is my first example he must not
have come to work a very low chance
impossible he came to work so there's a
very very low chance this person came to
work he must not have come he must not
have come again this past participle
form of the verb here finally she must
not have forgotten she must not have
forgotten you could say she must not
have forgotten the report she must not
have forgotten her keys or just she must
not have forgot
some other information so again past
participle form of the verb is used here
she must not have forgotten blah blah
blah we can add some extra information
about what she must not have forgotten
so low possibility she forgot extremely
low so please keep in mind that when we
use the positive form it expresses near
100% possibility and with a negative
form near 0% possibility
near impossible so in this lesson I've
introduced present possibility example
sentences and past possibility example
sentences you'll notice here I haven't
introduced any future tense possibility
that's because in most cases we do not
use must to talk about future
possibility in those cases we use words
like probably like I'm probably going to
or I'll probably bla bla bla so we don't
generally use must to talk about the
future possibility there are a few cases
where we may use the word must but maybe
I can talk about that in a different
video for now I'd like to just focus on
present and past possibility with a few
examples here so I hope this lesson was
useful for you if you have any questions
or if you want to try to make a sentence
please feel free to do so in the
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good stuff as well thanks very much for
watching this episode and I will see you
again soon
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