THIS is a car. .
THAT is a bird.
THESE are cats. These are hats.
THOSE are bees.
1- "this" is used for an object (only 1) which is near the speaker.
2- "that" is used for one object which is far from the speaker.
3- "these" is used for objects (more than 1) which are near the speaker
4- "those" is used for objects (more than 1) which are far from the speaker.
Click on the following links to do online exercises.