this - that - these - those 

  THIS - THAT

         This is used to refer to a single person, thing, place that is close to the speaker.

         That is used when the person, thing, place is more distant.

                               ◊  This computer is easy to use.

                               ◊  That coat on the chair is mine.

                               ◊  This person is my colleague.

                               ◊  That man over there is my boss. 

                                ◊ This picture is clearer than that one.
 

                                                               THESE - THOSE

          These is the plural form of this.

          Those is the plural form of that.

                                ◊  These letters are urgent.  Please post them immediately.

                                ◊  Those men in the street are policemen.

                                ◊  I like these shoes.  They're very comfortable.

                                ◊  Those shoes on the shelf are too expensive.

                                ◊  I like these shoes better than those shoes