بیان توانایی با افعال کمکی

Hi. Hey, want to see what I can do? Watch this. Did you see that? Did you see what I can do? I can do a handstand. How about you? Can you do a handstand? What can you do? Today, I want to talk to you
about how to express ability and inability in English, using the words can,
could and be able to. Do you know what kind of verbs these are? If you said modal verbs, you're right. So, how about it? Do you want to learn how to use
these words to express ability? I'll teach you, come with me. Let's start with ability
in the present and future. These babies can touch their toes! We can also say,
these babies are able to touch their toes! We use the modal verb, can,
and the phrasal modal verb, be able to, to express ability. Because these are modal verbs, they're followed by the simple
form of the main verb. Can you find the main
verb in these sentences? That's right, it's touch. So these two sentences mean
exactly the same thing. But let's take a look at
the first one to see how it's a little bit different in its
form than the second one. When we use can,
all we need is any subject. Followed by can, remember no s, and a main verb in its simple form. To make it negative, we can say cannot or
the contraction can't. For example, this baby can't walk. She can only crawl. Unlike can, be able to will
change according to the subject. For example we say, I am able to. You, we, they are able to and he, she, it is able to all followed by the main verb. To make it negative, we simply add not. For example, she is not able to walk. Okay, let's take a look
at ability in the past. When Joe was younger,
he could touch his toes. Now, he can't. Poor Joe. We can also say when Joe was younger,
he was able to touch his toes. Now he can't. We use the modal verb could to
express ability in the past. We have another clue in this sentence that
tells us we're talking about the past. Can you find it? Yep, it's the verb was,
which is in its past form. Just like can, could is easy to use. We don't need to change it
according to the subject. To make it negative, we simply add not or
use the contraction couldn't. Be careful with be able to in the past. There are two different forms. We can say I, he, she and it was able to. And you, we, they were able to. To make it negative, we simply add not. Was not able to and were not able to. Okay, let's review what we learned. To express ability in the present and
future, we can use can or
cannot to express inability. And the main verb in its simple form. To express ability and
inability in the past, we can use could or
could not, and let's not forget the contractions,
can't and couldn't. We can also use the phrasal modal verb, be able to, to express ability
in the present and future. And in the past. I hope you had fun learning how
to express ability in English.