Nowadays we can find advertisements almost everywhere. We are so used to them

  43    we often do not realize how many we see or hear a day.

An advertisement uses words and pictures to persuade people to buy a product or service, or to believe an idea. Newspapers, magazines, the Internet, radio and television are    44   most common places to find them. There are   45   main types of advertisements—commercial advertisements and public service advertisements (PSAs).

A commercial advertisement is one which someone has paid for to advertise a product or service. PSAs are often run for free, and are meant to educate people about health, safety or any other problem   46   affects public welfare.

Most of these ads are meant to benefit the public, and you can often learn a lot   47    following the advice they give.   48   , some false ads play tricks on us, fooling us into consumptions. So,    49   it comes to advertisements, we must use our intelligence and not to be   50   slave to them.