To be needed, wanted by a lot of people

To be exceptionally good at or proficient in something

To keep something easily accessible

just in case

To speak negatively about someone

extremely important

a person who is good at dealing with other people

To coincide with 

To study something as your main subject at  university or college

To chit-chat, have a conversation about

unimportant things, often between people who do not know each other

To offer a helpful response to someone’s work