ことが出来る・できる

Phrase (Basic ㊦ 200)

Doing something is possible

Equivalent: Can; be able to

田口さんは中国語を話すことが出来る・出来ます。: Mr. Taguchi can speak Chinese.
新幹線に乗れば大阪まで三時間で行くことが出来る。: If you take the bullet train, you can get to Osaka in three hours.
小田さんは六つの時バッハを弾くことが出来た。: Oda was able to play Bach at the age of six.
ジョンソンさんは日本語で手紙を書くことが出来る。: Mr. Johnson can write letters in Japanese.

Formation

Vinformal nonpast	ことが出来る
	話すことが出来る	Someone can talk
	食べることが出来る	Someone can eat

Notes

1. Verb informal nonpast ことが出来る is a potential form meaning 'can' or 'be able to ~'. This potential form is used in the "は~が construction":

Noun (animate) は (~Verb informal nonpast) ことが出来る.

where Noun is an animate experiencer and the noun phrase ~Verb informal nonpast こと is a subject noun phrase nominalized by こと. The meaning of the structure is 'Noun can Verb' (Literally: 'For Noun, Verbing~ is possible.').

(⇨ は~が)

2. If a verb is closely associated with its direct object, as in (1) and (2) below, をVerbこと can be deleted.

ナンシーはピアノ(を弾くこと)が出来る。
Nancy can play the piano.

岡本さんはロシア語(を話すこと)が出来る。
Mr. Okamoto can speak Russian.

The をVerbこと deletion is unacceptable in the following sentence, however, because there is no close association between the verb and its direct object.

スミスさんは日本語の新聞{を読むこと/*∅}が出来る。
Mr. Smith can read Japanese newspapers.

【Related Expression】

A shorter potential form of verb, i.e., られる2 can replace the longer potential form ことが出来る without a change in basic meaning. Thus, Examples (a), (b) and (c) can be rewritten as [1], [2] and [3], respectively.

[1]

新幹線に乗れば大阪まで三時間で行ける。

[2]

小田は六つの時バッハが/を弾けた。

[3]

ジョンソンさんは日本語で手紙が書ける。

Basically, the difference between the shorter and the longer potential form is one of style; namely, the shorter version is more colloquial and less formal than the longer one.