Cách sử dụng
The expression "in an undertone" means to speak in a quiet or low voice, usually with the intention of not being heard by everyone around. It is typically used in situations where you want to have a private conversation with someone else without others listening in or being disturbed. For example, if you're discussing something confidential with a friend in a public place, you might speak in an undertone to make sure no one else overhears your conversation.