He is experiencing the difficulties of puberty.

According to Freud's theory, the phallic stage is a part of a child's sexual development.

Mothers in the lactation period should strive for a well-balanced diet.

I am a new student of this school.

Apologizing at this point is too late.

This is the dawn of a new science.

He is still in his tsun phase, so he doesn't talk much.

She is in her dere phase now.

A new school term is starting.

His dog is currently in its sexually active period.