بیان عدم امکان با افعال کمکی

Modal verbs, can't and couldn't,
impossibility or disbelief. [NOISE]
>> Someone's at the door. >> Is it your mom? >> It can't be my mom,
she's out of the country. [NOISE] Whoa, is it your neighbor? >> It couldn't be my neighbor,
he's at work right now. [NOISE]
>> Who could it be? >> Can't and couldn't,
these modal verbs express impossibility or disbelief in the present. >> For example,
my mom can't be at the door. She's traveling to another country. It's impossible! >> For impossibility and disbelief,
can't and couldn't have the same meaning. >> It can't be my neighbor, or
it couldn't be my neighbor. He's at work right now. >> It can't be my neighbor is the same as it couldn't be my neighbor. Can't and couldn't show that
someone is not 100% certain. >> I can't see who it is,
so I don't know for sure. However, I'm almost certain it
isn't my mom or my neighbor. >> [NOISE] Hi, thank you. >> I was right, it wasn't my mom or
my neighbor, it was the postman. >> Well, what is it? >> I have no idea. >> Well, it can't be your phone,
it's too big. >> Yeah, clearly, and it's obviously
not my new bike because it's too small. What could it be? >> Okay, let's remember,
like other modal verbs, can't and couldn't will come before
the simple form of the main verb. With this use,
the main verb is almost always be. >> For example,
it can't be my new phone in this box. The box is much too big. It's your turn. What's in the box? Here are some hints. Number one, it won't break if you drop it. >> Number two, you can wear it. >> Number three,
you can't eat it or drink it. >> And number four, it is not heavy. Okay, put the words in
the appropriate order. Make sentences using can't or couldn't to express impossibility
about what is in the box. Are you ready? Okay. >> Number one,
it couldn't be delicious candy. >> Number two, it can't be my new glasses. >> Number three,
it couldn't be a heavy book. >> Number four,
it can't be expensive perfume. Did you get it? Good job! Okay, let's review. >> What are two modal verbs we can use
to express impossibility or disbelief? >> That's easy, can't and couldn't. >> You're so smart. And what verb usually comes after can't or
couldn't? >> That's easy too, it's be! >> You got it! Okay, one last question. If I use can't or couldn't to express
impossibility, am I 100% certain? >> No, you are almost 100% certain.