The rich are not always happy. 

The cat is cute.

Rich is not always happy.   = Rich are not always happy.

Would you mind closing the door

The book is on the table.

Everybody have gone there.   = Everybody has gone there.

I am going to market.

He has been living here for five years.

One of my friends are a lawyer.   = One of my friends is a lawyer

Necessity does not obey any law

I prefer writing to reading.

গতরাতে তার ঘুম ভাল হয়েছে।  = He slept a sound sleep last night.

I couldn't but laugh.

তিনি এলএলএম পাশ।   =. He is an LLM.

The noun form of the word "foolish" is "foolishness"