阅读理解
Millions of people around the world cook their food over a smoky fire every day.It is often difficult to
find wood for the fire.People who do not have wood must spend large amounts of money on cooking fuel.
However,there is a much easier way to cook food using energy from the sun.
Solar cookers,or ovens,have been used for centuries.A Swiss scientist 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 harmful organisms.
There are three kinds of solar ovens.The first is a box cooker.It is designed with a special wall that
shines or reflects sunlight into the box.Heat gets trapped under a piece of glass or plastic covering the top
of the cooker.A box oven is effective for slow cooking of large amounts of food.
The second kind of solar oven is a panel cooker.It includes several flat walls,or panels,that directly
reflect the sun's light onto the food.The food is inside a separate container of plastic or glass that traps heat
energy.People can build panel cookers with very few supplies quickly.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(抛物线的) cooker.It has rounded walls that aim sunlight
directly into the bottom of the oven.Food cooks quickly in parabolic ovens.However,these cookers are
hard to make.They must be reaimed often to follow the sun.Parabolic cookers can also cause burns and
eye injuries if they are not used correctly.
You can make solar ovens from boxes or heavy paper.They will not catch fire.Paper burns at two
hundred thirtytwo degrees Celsius.A solar cooker never gets that hot.Solar ovens cook food at low
emperatures over long periods of time.This permits people to leave food to cook while they do other
things.
1．Which of the following should be the best title for this text?
A. Cooking food with solar energy
B. How to make solar cookers
C. Introduce a new kind of energy
D. Different kinds of cookers
2．From this passage we know that ________.
A. there is no wood for people to use while making a fire now
B. people have been using solar cookers for more than 200 years
C. solar energy is the cleanest energy on the earth
D. more and more people cook food on smoky fires
3．Parabolic cookers may be dangerous to us because ________.
A. they may direct electricity to us humans
B. they may explode easily
C. they may cause burns and eye injuries
D. they may cause fires
4．The third,fourth and fifth paragraphs mainly ________.
A. show how to make solar cookers
B. explain which is the best cooker
C. prove that solar cookers need improving
D. tell us the different making ups of the three kinds of solar cookers
拔除一年，缺牙间隙大，余留牙正常，可摘局部义齿修复，基牙
设计弯制卡环
为一类导线，应采用哪类卡环（）
面远，远缺隙测距