Naphthalene is a compound often used in organic chemistry.

In the organic chemistry experiment, we used phthalein as an indicator.

I was shocked when his duplicity became apparent.

It takes twenty minutes to get to my house.

The two-day trip was very enjoyable.

Both of my parents are doctors.

This project is a big burden for me.

My friend has twin brothers.

There are two rooms in my house.

My younger sister is twenty-two years old.