He understands the risk of being infected with semen that contains HIV.

The problem of introduced species can potentially disrupt the balance of ecosystems.

Many native species live in this park.

I use koji starter to make homemade miso.

What is the specific epithet of this plant?

This reaction occurs through a chemical process.

He is an excellent chemist who made many discoveries.

He is an expert in petrochemistry.

It's difficult to decipher this chemical equation.

Understanding chemical equations is difficult.