The leisure industry occupies an important part of the economy.

She is temporarily off work to take maternity leave.

Traffic cones have been set up due to road construction.

In chemistry class, I learned about basic oxides.

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

In chemistry class, I learned about the reactions of acid anhydrides.

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.

Essential amino acids cannot be produced in the body, so they need to be obtained from the diet.