BBC英語學習[6 Minute Grammar]系列-Session 2
Catherine
Hello and welcome to 6 Minute Grammar with me Catherine…
Neil
And me, Neil. Hello.
Catherine
In this programme we’re talking about modal verbs of ability.
Neil
Yes, we are. We』ll explain what they are …
Catherine
We』ll give you some useful tips on using them…
Neil
There』ll be lots examples …
Catherine
And of course we』ll finish with a quiz.
Neil
So here we go. First of all, what are modals of ability?
Catherine
Well, there are lots of different modal verbs like must, might and have to. We use them together with main verbs, to add meaning to what we say.
Neil
So in this programme we’re talking about the modal verbs can and could. We’re looking at how we can use these modals with main verbs to add meaning related to ability. Here’s Mike with an example.
Mike
Humans can only live without water for three to five days.
Catherine
So that’s can with the verb live to express ability: in this example, the ability to live without water. And in this programme we’re also going to talk about ability with the phrase be able to plus a verb. It’s similar to can, but it’s particularly useful when we’re suggesting that something is a bit surprising like this from Mike.
Mike
Humans can only live without water for three to five days. However, they are able to live without food for up to three weeks.
Neil
Okay. In those examples we’re talking about ability in the present. Now for the past.
Catherine
Yeah, the past. And the past of can is could. We also use be able to in the past but of course it becomes was able to or were able to. Listen.
Mike
People in Asia could write before people in Europe.
Catherine
Or…
Mike
People in Asia were able to write before people in Europe.
Neil
But sometimes you have to use be able to and not could.
Catherine
And that happens when we’re talking about a single event in the past, not general ability.
Neil
Exactly. Another example please, Mike.
Mike
After climbing for six hours, they were able to reach the top of the mountain.
Catherine
You can’t use could in that example because could is for general ability, not a single occasion like climbing one mountain.
Neil
But there is another verb that you can use in that last sentence. Have a listen.
Mike
After climbing for six hours, they managed to reach the top of the mountain.
Neil
Thank you Mike. We often use manage to with a verb for ability if something is very difficult to do or if something is very successful.
Catherine
Exactly. Remember that can and could are always followed by the infinitive without to(不定式). And they are the same for all subject pronouns.
Neil
Right. But be able to changes for different persons. It’s am/is/are able to for the present and was/were able to for the past.
Catherine
And we’re looking at modal verbs of ability.
Neil
Yes, we are. And we』ve got a few extra tips for you today.
Catherine
We have. And the first tip is, you know, sense verbs like see, hear and smell? And verbs of thinking like believe, understand and remember? Well, we usually use can and not be able to with those. Examples please, Mike.
Mike
I can’t understand this question.
Catherine
Good. Second tip. When we have two main verbs together, we can’t put can or could between them. For example, with the sentence I』d like to swim. It’s okay to say… I』d like to be able to swim. But it’s not okay to say… I』d like to can swim.
Neil
Oh no, you can’t say that! It sounds a bit strange.
Catherine
Yes, horrible.
Neil
Third tip: There is also no present perfect form of can. If we need the present perfect for ability, we use be able to. An example, please?
Mike
He hasn’t been able to walk since the accident.
Catherine
Thank you, Mike. And now a tip about manage to in the negative form. We say can’t manage to in the present, but it’s couldn’t manage to or didn’t manage to in the past.
Mike
I can’t manage to swim that far! (the present)
Fifty five pies?! I can’t manage to eat all those. (the present)
The men couldn’t manage to lift the piano. (the past)
He didn’t manage to get the grades he needed for university. (the past)
Catherine
Okay, thank you, Mike. And now - it’s quiz time. Will you manage to get three correct answers?
Neil
Let’s see. Are these sentences correct or incorrect?
1: The villagers were good hunters, but they couldn’t grow crops.
2: My phone wasn’t working but the receptionist could phone for a taxi.
3: I want to can do this.
Catherine
1:That’s correct.
2:That’s not correct. The correct sentence is the receptionist was able to phone for a taxi.
3:nd that’s not correct. Between two main verbs, we have to use be able to. So the correct sentence is I want to be able to do this.
Congratulations if you managed to get them all right! Yes. Well done!
Extra take away tips:
1.Sense verbs like see, hear and smell? And verbs of thinking like believe, understand and remember? Well, we usually use can and not be able to with those
2.When we have two main verbs together, we can’t put can or could between them
3.There is also no present perfect form of can
4.We say can’t manage to in the present, but it’s couldn’t manage to or didn’t manage to in the past.