The sky was threatening, so I decided to go out with an umbrella.

Her dress was in a black-and-white tartan pattern, and it was very nice.

Her dress was adorned with a beautiful floral pattern.

He drew a perfect circle on the blackboard.

He is good at distinguishing between characters in his drawings.

He is good at distinguishing and depicting the emotions of characters.

He is good at solving geometry problems.

He is good at geometry.

Differential geometry is a field of mathematics that studies geometric objects such as curves and surfaces using differential and integral calculus.

Understanding geometric series is important in learning the basics of advanced mathematics.