题干

下面是某生态农场生产流程示意图,据图判断,下列说法正确的是(   )

A:能量经过多级利用,实现了生态系统能量的良性循环

B:由于食物链延长,能量逐级损耗,系统总能量利用效率降低

C:当蚯蚓利用食用菌杂屑并将其同化为自身的有机物时,能量就从第三营养级流入第四营养级

D:每一环节部获得产品,循环利用了农业有机废弃物,提高了生态效益和经济效益

上一题 下一题 0.0难度 选择题 更新时间:2015-03-24 06:11:22

答案(点此获取答案解析)

D

同类题3

根据短文内容, 从下面方框内的七个选项中选出五个还原到短文中, 使原文句子通顺, 结构完整。

A. He also wrote the sport's official rules.

B. Soccer is the world's favorite sport.

C. Playing soccer is good for your health.

D. But one reason is how simple the sport is.

E. People love soccer as well as their countries.

F. It's hard to say where soccer's birthplace is.

G. Soccer performances are pleasing to the eyes.

    ____ It has around 3 billion fans—nearly half the world's population! And about 300 million people play this game. That's 4 percent of the world's population!

    ____ Many people in old days played the early form of this modern game. Cuju(蹴鞠), a ball-kicking game in China, was reported as early as 2, 500 B. C.  Around the same time in Greece, people were also playing a similar ball game without using their hands.

But modern soccer didn't become official(官方的)until 1863. An Englishman called Cobb Morley introduced the idea of a soccer association(联盟). ____ From then on, other associations in the countries were set up. They came together—to make up the FIFA, which organizes the World Cup.

It's not easy to tell what makes soccer so popular. ____ Soccer needs only two feet and a ball. This makes it a sport that developing countries can play easily. Some of the sport's best players come from these poor nations. 

    ____ The sport's no-hands rule makes beautiful dance—like movements on the field. What's more, this sport excites the heart. Teams might score only a few times each match, so matches can turn around suddenly.

     No one knows who will win at the next World Cup. But one thing is certain: The world will be watching.