He joined the demonstration while humming The Internationale.

He is an expert in international relations.

We camped in a densely wooded area.

According to the law on specified alien species, the import of certain organisms is prohibited.

He is good at solving trigonometry problems.

This library adopts its own classification method.

He surprised people by using magic.

Understanding patent law is important for protecting new inventions.

Ex post facto laws pose a problem for a fair legal system.

He conducted the trial based on common law.