She used to be a prostitute, but now she has started a new life.

Will you marry me?

"Do you want to have a meal? Take a bath? Or choose me?" she said jokingly.

He was hiding the fact that he was an illegitimate child.

I am majoring in microbiology at university.

Astrobiology is a very interesting field of study.

He is an expert in paleontology.

He is an expert in aerobiology, engaged in the study of microorganisms in the atmosphere.

He is an expert in biophysics.

Molecular biology is a field of study that understands life phenomena at the molecular level.