In chemistry class, I learned about basic oxides.

In chemistry class, I learned about acidic oxides.

Bioweapons are a major threat to humanity.

In this experiment, we will observe the reaction of organic compounds.

In this experiment, we will use various inorganic compounds.

He is good at playing the contrabass.

My younger sister won the piano contest.

He always carries a condom with him.

It is important to understand the basis of this problem.

This train is crowded every morning.