Using こと、もの

Koto - intangible things

いい事はありません。
ii koto wa arimasen.
There isn't anything good.

大事な事を教えます。
daiji na koto o oshiemasu.
I will tell you an important thing.

昨日の事はすみませんでした。
kinou no koto wa sumimasen deshita.
I am sorry about what happened yesterday. (yesterday's thing)

Mono - tangible things

その黒いものは猫かなあ。
sono kuroi mono wa neko kanaa.
I wonder if that black thing is a cat?

おいしいものが食べたい。
oishii mono ga tabetai.
I want to eat something good.

One useful phrase using koto is:

どういうこと？
dou iu koto?
What is the meaning of this?

This phrase is used whenever the listener isn't sure of the motive of the speaker.