He was observing the distant birds using binoculars.

This area is rich in peridotite.

This mountain is made of tuff.

This rock is gabbro.

He is majoring in petrology at university.

The students lined up in response to the teacher's instructions.

He cleaned the bowl of the pipe thoroughly.

This cigarette contains carcinogens.

I used binoculars to observe birds in the mountains.

It is said that this substance has a high carcinogenicity.