She has mastered the technique of facesitting.

Einstein proposed the theory of relativity.

His actions always have a duality.

My younger brother caught the influenza.

This material has high corrosion resistance.

The prevention of venereal diseases is most important in safe sexual behavior.

This equation has homogeneity.

Radioactive elements are produced in nature and scientific experiments.

He was diagnosed with bipolar disorder.

This software has forward compatibility.