Learning homonyms in Japanese is difficult.

He is majoring in zoology at university.

My friend came from Equatorial Guinea.

My colleague is very helpful.

The hardware of my computer is getting old, so I need to replace it with a new one.

I attend a calligraphy class every week.

He checks the daily news reports.

Animal experiments are necessary for the advancement of science, but there are also ethical issues.

He is learning about the handling of experimental animals.

Morality is an important element for smoothing human relationships.