He fell into deep thought.

My great-grandfather used to do farming in the past.

My great-grandfather was a doctor.

My great-grandfather was a doctor.

My great-grandfather was a doctor.

My paternal grandfather once traveled all over Japan when he was young.

He fell into a state of lethargy after the exam.

Understanding the transition state of a chemical reaction is important for predicting the progress of the reaction.

The negotiations have fallen into a deadlock.

He ended up in a vegetative state after the accident.