The products of this region are very delicious.

In chemistry class, I learned about basic oxides.

Amphoteric oxides have the characteristic of reacting with both acids and bases.

Acidic oxides react with water to produce acids.

Aluminum is an amphoteric oxide, it reacts with both acids and bases.

Basic oxides react with acids to produce salt and water.

Do you understand the necessity of this project?

That information is unnecessary.

That information is completely unnecessary.

He thinks that war is a necessary evil.