He was plowing and weeding the rice field all day.

He was plowing and weeding in the rice field all day.

It's difficult to solve this formula.

Vitamin D3 is an important nutrient for bone health.

I like making sandwiches.

Traffic cones have been set up due to road construction.

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

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

In chemistry class, I learned about basic oxides.

Acidic oxides react with water to produce acids.