Can,Cloud and be able to

1.       could: Past Possibility or Ability

We use could to talk about what was possible in the past, what we were able or free to do:

• I could swim when I was 5 years old.
• My grandmother could speak seven languages.
• When we arrived home, we could not open the door. (...couldn't open the door.)
• Could you understand what he was saying?

We use could (positive) and couldn't (negative) for general ability in the past. But when we talk about one special occasion in the past, we use be able to (positive) and couldn't (negative). Look at these examples:

	Past
	General	Specific Occasion
+	My grandmother could speak Spanish.	A man fell into the river yesterday. The police were able to save him.
-	My grandmother couldn't speak Spanish.	A man fell into the river yesterday. The police couldn't save him.

2.       could: Requests

We often use could in a question to ask somebody to do something. The use of could in this way is fairly polite (formal):

• Could you tell me where the bank is, please?
• Could you send me a catalogue, please?

Be able to

Although we look at be able to here, it is not a modal verb. It is simply the verb be plus an adjective (able) followed by the infinitive. We look at be able to here because we sometimes use it instead of can and could.

(Meskipun kami melihat “be able to”di sini, itu bukan kata kerja dengan modal. Ini hanyalah kata kerja be ditambah kata sifat (able) diikuti oleh infinitive. Kami melihat “be able to” di sini karena kita kadang-kadang menggunakanny, bukannya can dan could.)

We use be able to:

v to talk about ability

Structure of Be able to

The structure of be able to is:

subject + be + able + infinitive

	subject	be main verb	able adjective	infinitive
+	I	am	able	to drive.
-	She	is not	able	to drive.
		isn't
?	Are	you	able	to drive?

Notice that be able to is possible in all tenses, for example:

• I was able to drive...
• I will be able to drive...
• I have been able to drive...

Notice too that be able to has an infinitive form:

• I would like to be able to speak Chinese.

Use of Be able to

Be able to is not a modal auxiliary verb. We include it here for convenience, because it is often used like "can" and "could", which are modal auxiliary verbs.

(Be able to bukan kata kerja bantu seperti modal. Kami sertakan di sini untuk kenyamanan, karena sering digunakan seperti "can" dan "could", yang merupakan kata kerja bantu modal.)

v be able to: ability

We use be able to to express ability. "Able" is an adjective meaning: having the power, skill or means to do something. If we say "I am able to swim", it is like saying "I can swim". We sometimes use "be able to" instead of "can" or "could" for ability. "Be able to" is possible in all tenses - but "can" is possible only in the present and "could" is possible only in the past for ability. In addition, "can" and "could" have no infinitive form. So we use "be able to" when we want to use other tenses or the infinitive.

(Kami menggunakan be able to untuk mengekspresikan kemampuan. "Able" adalah sebuah kata sifat yang berarti: memiliki kekuatan, keterampilan atau sarana untuk melakukan sesuatu. Jika kita mengatakan "Saya bisa berenang", itu adalah seperti mengatakan "Saya bisa berenang". Kami kadang-kadang menggunakan "dapat" bukan "kaleng" atau "bisa" karena kemampuannya. "Mampu" adalah mungkin dalam beberapa bentuk kata semua - tetapi "bisa" hanya mungkin di masa kini dan "bisa" hanya mungkin di masa lalu karena kemampuannya. Selain itu, "bisa" dan "bisa" tidak memiliki bentuk infinitif. Jadi kita menggunakan "dapat" ketika kita ingin menggunakan tenses yang lain atau infinitive.)

Look at these examples:

• I have been able to swim since I was five. (present perfect)
• You will be able to speak perfect English very soon. (future simple)
• I would like to be able to fly an airplane. (infinitive)