He engaged in an extravehicular activity from the spaceship.

He is undergoing training for extravehicular activity.

He is a foreigner, but he can speak Japanese fluently.

This book explains in detail about the use of foreign words.

I use a set square to draw shapes.

In chemistry class, I learned about acid anhydride.

In chemistry class, I learned about acidic oxides.

Lower fatty acids play an important role in the human body.

Essential fatty acids are necessary to be taken from our diet because our body cannot produce them on its own.

Essential amino acids are vital nutrients for the human body.