He couldn't hide his remorse for the failure.

If you rephrase that complex theory in simpler terms, it's just common sense.

He daringly accepted the challenge.

He drew a circle.

I gathered the stalks of millet and used them as livestock feed.

His thought is deep.

His character affects all the people he is involved with.

The road caved in and was closed to traffic.

I am studying Korean language.

He is a famous film director.