Can and Be Able To
Modal verbs are helping verbs.
情態動詞是助動詞
We use them with main verbs to help us express ability, possibility, necessity and permission.
我們將它們與助動詞連用，以幫助我們表達能力、可能性、必要性和許可
Today’s question is about a modal that is commonly confused with an expression.
今天的問題與一個情態動詞有關，這個詞通常與一個表達混淆
Here’s the question, which comes from a listener named Cafer:
下面是一位叫名叫Cafer的聽眾提出的問題：
Question
Hi! Would you like to explain the difference between 「can」 and 「be able to」? Thank you. -Cafer ?zcan
你好，你能解釋一下can和be able to的區別嗎？謝謝
Answer
Hi, Cafer!I can explain the differences between the two.
你好，Cafer！我可以駕駛這兩者之間的區別
I just used 「can」 to talk about my ability to do something.
我只是用can來表達我做某事的能力
We also use 「be able to」 for abilities, but usually only when 「can」 is not possible.
我們也用be able to來表達能力，但通常只在can不能用的時候才用
I』ll tell you what that means in a minute.
我一會會告訴你那是什麼意思
But first, let’s explore the word 「can.」
但首先，讓我們探討一下can這個詞
Can
「Can」 is a modal verb. We use it to talk about present or future ability or possibility.
「can"是情態動詞。我們用它來談論現在或未來的能力或可能性
You must use 「could」 for the past tense, such as in, 「You could have bought the tickets online.」
你必須用could來表示過去時，例如，You could have bought the tickets online
We also use 「can」 ：to ask for or give permission.
我們也在下列情況中使用can：請求或給予許可
I am finished. Can I go now?
我做完了，我現在可以走了嗎？
Yes, you can.
好的，你可以走了
and to ask someone to do something
要求某人做某事
Can you bring me the magazine?
你能把雜誌拿給我嗎？
Be able to
Now, let’s explore 「be able to.」
現在，讓我們探討一下be able to這個表達
This expression is not a modal.
這個表達不是情態動詞
It is the verb 「to be」 plus the adjective 「able.」
它是由動詞to be加上形容詞able組成
The word 「to」 shows that an infinitive verb will follow.
to這個詞表示後面會跟動詞原形
We use 「be able to」:when it is not possible to use 「can」 for abilities, such as after other modal verbs.
當不能用can表達能力時，我們就用be able to,例如，在其他情態動詞之後
The words 「won’t」, short for 「will not」, and 「should」 are modals.
」won't"是will not的縮寫，它和should都是情態動詞
In English, we do not put two modals together.
在英語中，我們不能把can放在他們後面
So, we cannot put 「can」 after them.
所以，我們不能把can放在他們後面
We also use 「be able to」:to talk about small or large past successes.
我們也用be able to來表示過去或大或小的成功
But in negative form, we can use "be able to」 or 「could」.
但在否定形式中，我們可以用be able to或could
But note that the negatives "wasn’t able to" and "weren’t able to" are a little more formal than "couldn't."
但是要注意，wasn't able to和weren't able to這兩種否定形式比couldn't更正式一點。
And that’s Ask a Teacher.
I’m Alice Bryant.
Do you have a question for Ask a Teacher, write to us in the comments area. Be sure to tell us what country you are from.
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Words in This Story
confuse – v. to make someone unable to understand something
guitar – n. a musical instrument that is held against the front of your body and that has six strings
infinitive – n. the basic form of a verb
negative – adj. describing a word or statement that means 「no」 or that expresses a denial or refusal.
來自：VOA英語網 文章地址: http://www.tingvoa.com/19/01/Can-and-Be-Able-To.html