Using punctuation marks correctly is important for understanding sentences.

What is this solid made of?

There are sediments at the bottom of this lake that have accumulated over centuries.

What is this mixture made of?

This structure was built centuries ago.

This is the souvenir I brought back from my trip.

My favorite mode of transportation is the train.

By regularly checking the key performance indicators, you can understand the performance of the company and devise improvement measures.

His art style is unique, it's neither fish nor fowl.

The study of organic compounds is an important field in chemistry.