It's difficult to decipher this chemical equation.

This problem is very difficult.

It took him a week to decipher the ancient document.

He succeeded in deciphering the ancient documents.

He is majoring in chemistry at university.

We will attend a wedding ceremony tomorrow.

He is an expert in chemistry.

This math problem can be solved using a specific formula.

We have our wedding ceremony tomorrow.

Oxygen, which is one of the chemical elements, is necessary for us to breathe.