Homo erectus is considered one of the ancestors of mankind.

He is deeply studying the philosophy of nihilism.

The northern elephant seal is a large marine mammal that mainly lives in the northern hemisphere.

I have been to Jiulong.

She loves Gothic architecture.

The airplane lost altitude rapidly due to the downdraft.

I am majoring in parasitology at university.

He is an expert in parasitology and conducts many researches.

An imaginary unit is an important concept in mathematics.

Mr. Kaiboku is my best friend.