I am learning how to use the present participle in English.

The present tense is used to express things that are happening now or general facts.

He has already finished writing the report, so we use the present perfect form.

Right now, I am in Tokyo.

I want to go to Mongolia.

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.