During periods of low stock prices, you should be cautious about investing.

Ayumi is my best friend.

He is enjoying reading in a quiet place.

Wei An is my best friend.

My friend came from Anqing.

He found a place to ease his body in this town.

Annam is the old name of Vietnam.

Ammonium carbonate is a compound commonly used in inorganic chemistry.

Ammonium nitrate is widely used in the manufacture of fertilizers and explosives.

In chemistry class, I learned about the properties of ammonium chloride.