B

　　How can cactus (仙人掌) help the world？It can provide a new kind of sustainable fuel (可持续燃料).Nopalimex, a company in Mexico, has made one of the world’s first cactus-powered factories. The  idea came to Sosa  in  Nopalimex when he was looking for ways to save money for his food factory. He now powers his factory with cactus gas (气体)． The cost to produce the gas is half the cost of electricity．

　　Soon， the gas produced by Nopalimex will also be used in cars．Nopalimex's gas is made by using the prickly pear （刺梨）, a kind of cactus．To make the gas，the prickly pear is mixed together with manure （肥料）. Then the mixture produces the gas that can be used as fuel．

　　Why cactus？Fuel can be made from other plants such as corn，but there are a few reasons why cactus is a better choice． First， prickly pears need very little water and very lite care， and grow well in hot temperatures． Today， these characteristics （特点） are key． Also， unlike corn， prickly pears don't need space that could be used for other food plants． They can grow in areas where many food plants can′t grow． Last，after making gas from prickly pears and manure， their byproducts （副产品）can be used to help grow food．

　　Scientists still need to do more research on making and using prickly pear gas． As projects like Nopalimex show， we have the possibility to produce more sustainable fuel to power our lives．

　　14．How can cactus help the world？

　　A． By saving farmers' money．

　　B． By providing a new kind of sustainable fuel．

　　C． By taking the place of corn．

　　D． By producing a lot of electricity and gas．

　　15．Why does Sosa power his factory with cactus gas？

　　A． Because he wants to save money for his food factory．

　　B． Because he has grown a lot of cactus and com in his town．

　　C． Because he wants to be well﹣known around the world．

　　D． Because he wants to grow cactus instead of corn．

　　16．What does the underlined word "mixture" in Paragraph 2 refer to（指代）？

　　A． The Nopalimex company．

　　B． The manure．

　　C． The prickly pear and manure．

　　D． Cactus．

　　17．What is Paragraph 3 mainly about？

　　A． How cactus is used to produce gas．

　　B． Where we can grow a lot of cactus．

　　C． What Nopalimex does with cactus．

　　D． Why cactus is a better choice to make fuel．