Here’s a possible set of words to fill in the gaps:

Most of us buy a new pair of fashionable sunglasses each year. To be honest, we probably (11) **give** more thought into looking cool than we do into ensuring that the glasses match our needs. It seems an obvious thing to say, (12) **that** the main role of sunglasses is not actually to enhance your image. It is rather to protect your eyes from the potentially harmful rays of the sun. What’s (13) **more**, price is not necessarily the best guide (14) **to** the effectiveness of sunglasses. Indeed, expensive designer glasses may not provide the best defence against sun damage. (15) **Although** you may still want to choose a pair of sunglasses that look good on you, it is also crucial to check out just (16) **how** effective they will be in protecting your eyes. There are three types of light (17) **that** can harm the human eye. They are known (18) **as** ultraviolet light, visible light and infra-red light. If you (19) **take** the choice of sunglasses seriously, then you will want to protect yourself against all (20) **three**.