My mother underwent surgery for gallstones.

He is drawing a picture on a slate.

This building is made of marble.

He started a fire using a flint.

The capacity of this bottle is 500 milliliters.

I am responsible for the contents of this document.

We are friends who share joy and sorrow.

I am the person in charge of this project.

There are still vacant seats on this train.

The cumulative cost of this project is getting quite high.