做补全短文这类题，考生在解题时要特别注意空白处前后的句子成分，由此来判断此处所需的语法结构是句子、从句还是短语。如果空白处是在一句话的中间，则需要补全的为短语或从句;如果空白处是在句号的后面，则需要补全的是一个独立的句子。

下面的短文有5处空白，短文后有6个句子，其中5个取自短文，请根据短文内容讲其分别放回原有位置，以恢复文章面貌。

The Tough Grass that Sweetens Our Lives

Sugar cane was once a wild grass that grew in New Guinea and was used by local people for roofing their houses and fencing their gardens. Gradually a different variety evolved which contained sucrose (蔗糖) and was chewed on for its sweet taste. Over time, sugar cane became a highly valuable commercial plant, grown throughout the world. (46)

Sugar became a vital ingredient in all kinds of things, from confectionery (糖果点心) to medicine, and, as the demand for sugar grew, the industry became larger and more profitable.(47) Many crops withered (枯萎) and died, despite growers' attempts to save them,and there were fears that the health of the plant would continue to deteriorate.

In the 1960s, scientists working in Barbodos looked for ways to make the commercial species stronger and more able to resist disease. They experimented with breeding programmes,mixing genes from the more delicate, commercial type. (48) This sugar cane is not yet ready to be sold commercially, but when this happens, it is expected to be incredible profitable for the industry.

(49) Brazil, which produces one quarter of the world's sugar, has c~ordinated an international project under Professor Paulo Arrudo of the Universidade Estaudual de Campinas in Sao Paulo. Teams of experts have worked with him to discover more about which parts of the genetic structure of the plant are important for the production of sugar and its overall health.

Despite all the research, however, we still do not fully understand how the genes in sugar cane. (50) This gene is particularly exciting because it makes the plant resistant to rust,a disease which probably originated in India, but is now capable of infecting sugar cane across the world. Scientist believes they will eventually be able to gro.w a plant which cannot be destroyed by rust.

请在第__(46)__处填上正确答案。

A.Eventually, a commercial plant was developed which was 5 percent sweeter than before, but also much stronger and less likely to die from disease.

B.One major gene has been identified by Dr. Angelique D'Hont and her team in Montpelier, France.

C.Sugar cane is now much more vigorous and the supply of sugar is therefore more guaranteed.

D.Since the 1960s, scientists have been analyzing the mysteries of the sugar cane's genetic code.

E.The majority of the world's sugar now comes from this particular commercial species.

F.Unfortunately, however, the plant started to become weaker and more prone to disease.

47、请在第__(47)__处填上正确答案。

A.Eventually, a commercial plant was developed which was 5 percent sweeter than before, but also much stronger and less likely to die from disease.

B.One major gene has been identified by Dr. Angelique D'Hont and her team in Montpelier, France.

C.Sugar cane is now much more vigorous and the supply of sugar is therefore more guaranteed.

D.Since the 1960s, scientists have been analyzing the mysteries of the sugar cane's genetic code.

E.The majority of the world's sugar now comes from this particular commercial species.

F.Unfortunately, however, the plant started to become weaker and more prone to disease.

48、请在第__(48)__处填上正确答案。

A.Eventually, a commercial plant was developed which was 5 percent sweeter than before, but also much stronger and less likely to die from disease.

B.One major gene has been identified by Dr. Angelique D'Hont and her team in Montpelier, France.

C.Sugar cane is now much more vigorous and the supply of sugar is therefore more guaranteed.

D.Since the 1960s, scientists have been analyzing the mysteries of the sugar cane's genetic code.

E.The majority of the world's sugar now comes from this particular commercial species.

F.Unfortunately, however, the plant started to become weaker and more prone to disease.

49、请在第__(49)__处填上正确答案。

A.Eventually, a commercial plant was developed which was 5 percent sweeter than before, but also much stronger and less likely to die from disease.

B.One major gene has been identified by Dr. Angelique D'Hont and her team in Montpelier, France.

C.Sugar cane is now much more vigorous and the supply of sugar is therefore more guaranteed.

D.Since the 1960s, scientists have been analyzing the mysteries of the sugar cane's genetic code.

E.The majority of the world's sugar now comes from this particular commercial species.

F.Unfortunately, however, the plant started to become weaker and more prone to disease.

50、请在第__(50)__处填上正确答案。

A.Eventually, a commercial plant was developed which was 5 percent sweeter than before, but also much stronger and less likely to die from disease.

B.One major gene has been identified by Dr. Angelique D'Hont and her team in Montpelier, France.

C.Sugar cane is now much more vigorous and the supply of sugar is therefore more guaranteed.

D.Since the 1960s, scientists have been analyzing the mysteries of the sugar cane's genetic code.

E.The majority of the world's sugar now comes from this particular commercial species.

F.Unfortunately, however, the plant started to become weaker and more prone to disease.

答案解析

46. E

解析：空格前一句中讲到，甘蔗成了一种极具价值的商业作物，在全世界种植。根据因果关系和关键词“commercial plant”， “grown throughout the world”，E选项(现在世界上大部分糖都是产自这个特殊的商业作物)符合文义，故E为最佳选项。

47. F

解析：空格前提到对糖的需求增加，空格后提到植物枯萎并死掉。前后具有转折关系，所有选项中只有F含有转折词“however”，故F(然而不巧的是.这种植物开始变得柔弱起来，抗病性也越来越弱)是正确答案。

48. A

解析：空格前提到了科学家在20世纪60年代开始寻找方法让甘蔗这个植物更壮抗病能力更强，并进行不同植物基因混合的实验。空格后提到现在这种甘蔗植物还不准备用作商业用途。空格前后具有时间顺序，先是开始研究新的甘蔗品种，后是新的甘蔗品种还不打算商用，所以中间应该是新的甘蔗5品种已经研究出来了。故A(最后，一种经济作物被开发出来，不仅仅甜度上升了5%，同时更为强壮，抗病性更强)是正确答案。

49. D

解析：这个空格位于段首，应该是这个段落的总起句。空格后列举了例子来说明“Teams of experts have worked with him to discover more about which

Darts of the genetic structure of the plant are important for the production ofi sugar and its overall health.”即科学家为了发现更多的基因结构。提到“基因结构”的选项只有D，故D(自20世纪60年代起，科学家就一直在研究甘蔗基因代码的奥秘)是正确答案。

50. B

解析：空格前提到研究者们仍然无法完全了解基因的模式。空格后提到这个基因尤其令人兴奋，句意具有明显转折的意味，空格后的“this gene”j该指代空格所在句子的某个基因，故8选项(Dr.Angelique D’Hont和她在法国Montpelier的团队鉴定出了其中的一种基因)前后内容相符，是正确答案。