The act of watching or listening to something carefully.

To give classes in a particular subject at a school, university, etc.

Knowledge about a subject, situation, etc.

Many different types of things or people.

To tell someone another person’s name the first time that they meet.

Something that is similar to something else has many things the same, although it is not exactly the same.

Different and separate.

Relating to the things you do with other people for enjoyment when you are not working.

Polite and showing respect.