There are still vacant seats on the train.

Oil is an important element of the world economy.

I saw a wagtail in the park.

This rock has been here for hundreds of years.

Complex analysis is a branch of mathematics that studies functions of complex numbers.

He is an expert in harmonic analysis.

He is majoring in analysis at university.

Numerical analysis is a branch of mathematics that studies techniques and theories for solving mathematical problems numerically.

I can't forget the impression when I ate kaiseki for the first time.

This beautiful apophyllite is part of my treasure collection.