This rock is gabbro.

This area is rich in gabbro.

This rock has existed for millions of years.

This story depicts the life of an ancient judge.

This precedent will have a significant impact on future trials.

There is a counterexample to this math problem.

Please look at the legend of this map.

Please refer to this example.

He is an expert in petrology and is in charge of geology lectures.

Before the meeting started, he bowed to everyone.