She was diagnosed with placenta previa.

The issue of the previa vessel is a very important issue in obstetrics.

He is still young.

Whenever he faced a difficult situation, he always said, 'The best of the Thirty-Six Stratagems is to run away.'

In this chemical reaction, cyclohexane is the main product.

Cyclopentane is a compound often used in organic chemistry.

Cyclooctane plays an important role in organic chemistry.

I used cyclononadecane in an organic chemistry experiment.

This compound has cyclohexadecane as its main component.

This compound contains cyclotetradecane.