こと (1)

Noun (Basic ㊦ 191)

A thing which is intangible.

Equivalent: Thing; what

いいことを教えてあげよう・あげましょう。
I have a good suggestion for you.
論文に書いたことを話して下さい。
Please tell me what you wrote in your thesis.
ブラウンさんは日本の大学のことをよく知っている・います。
Mr. Brown knows a lot (of things) about Japanese universities.
大事なことはもう全部話しました。
I already told you everything that's important.
先生が言ったことを覚えていますか。
Do you remember what (=the thing which) the teacher said?
試験のことは忘れなさい。
Forget about the exam.

Formation

(i) {V/Adjective い} informal こと  
  {話す /話した} こと What someone (will) says/said
  {面白い /面白かった} こと What is/was interesting
(ii) Adjective な stem {な/だった} こと  
  {大事な/大事だった} こと What is/was important
(iii) Noun のこと  
  先生のこと Things about the teacher

Notes

1. こと means a thing which is intangible. Thus,(1) is ungrammatical.

2. Nounのこと, whose literal meaning is 'thing of Noun' is often used with such verbs as 知っている 'know', 話す 'talk' and 忘れる 'forget', and means 'know about Noun', 'talk about Noun', etc.

3. こと is used as a nominalizer, too. (⇨ こと2) Example (b), for instance, is ambiguous without proper context. That is, it means either 'Do you remember the thing which the teacher said?' or 'Do you remember (the fact) that the teacher said (it)?'

【Related Expression】

もの also means 'thing', but it means 'a tangible thing'. Compare こと and もの in the following sentences:

[1]

[2]