They (referring to women or girls) are my best friends.

The baby's umbilical cord is cut immediately after birth.

Japan is located in the temperate zone.

He underwent vocal cord surgery.

He lives on a tropical island.

My brother is a graduate student at the University of Tokyo.

He is a world-renowned researcher.

My laboratory is on the third floor of the university.

He is known as an excellent researcher.

I am a member of that research association.