填空题

(36) of people around the world cook their food over a (37) fire every day. It is often difficult to find wood for the fire. People who do not have wood must spend large (38) of money on cooking fuel. However, there is a much easier way to cook food using (39) from the sun.
Solar cookers, or ovens, have been used for (40) A Swiss (41) made the first solar oven in 1767. Today, people are using solar cookers in many countries around the world. People use solar ovens to cook food and to heat drinking water to kill bacteria and other (42) organisms.
There are three kinds of solar ovens The first is a box cooker. It is (43) with a special wall that shines or reflects sunlight into the box. (44) .
The second kind of solar oven is a panel cooker. (45) . People can build panel cookers quickly and with very few supplies. They do not cost much. In Kenya, for example, panel cookers are being manufactured for just two dollars.
The third kind of solar oven is a parabolic cooker. (46) . Parabolic cookers can also cause burns and eye injuries if they are not used correctly.