Which one is right? : People / Some people learn languages more easily than others.
Some people
Which one is right? : I went to the library and borrowed some books / books.
some books
Which one is right? : It might rain. Don't go out without umbrella / without an umbrella.
without an umbrella
What are these things? : Earth, Mars and Jupiter. They're a planet / planets.
planets
What are these things?: A mosquito. It's a insect / an insect.
an insect
What are these things?: The Nile, the Rhine and the Amazon. They're a river / rivers.
rivers
