He is receiving treatment for obsessive-compulsive disorder.

The sexology class is very interesting.

In mathematics, it is important to examine the parity of numbers.

Sex chromosomes play a crucial role in determining the sex of an organism.

Sex chromosomes play an important role in determining the sex of an organism.

This metal has very high malleability.

This new software has backward compatibility, so you can use old version data without any problems.

This new software maintains upward compatibility with the old version.

These two software have complete interchangeability.

Cats are digitigrade animals, they walk on their toes.