Everyone was surprised by the news.

My boyfriend gave me a gift.

He is studying the shape of a decahedron.

He threw a dice shaped like a hexahedron.

We are advancing the project using the waterfall model.

The waterfall model is one method of software development.

We use a numerical surface model to understand the topography of this area.

The hidden Markov model is a statistical method that is widely used in natural language processing and speech recognition.

He likes to take a walk in the park at dusk.

A positive number is a number greater than zero.