Salt is known to have a very strong corroding effect on metals.

by__________. 查看材料

A.melting of sea ice

B.precipitation

C.evaporation

D.supplement of salt

arch commemorating the seventy-fifth anniversary of the event which ultimately forced the India's British rulers to open talks on independence. Tushar Gandhi, with several hundred volunteers, will recreate the journey known as the Salt March to promote peace and religious harmony. Mahatma Gandhi had undertaken the original march in 1930. It made the British take note of his civil disobedience movement.

When did the India's British rulers open talks on India's independence？

A．Fifty years ago.

B．Fifty-five years ago.

C．Seventy five years ago.

D．Seventy seven years ago.

ds safe. The corrosive effects are well known, but for years they' re been dismissed with the argument that at around $ 25 a ton, salt is far cheaper than any alternative.

Lately, economists have added up the actual costs. The Environmental Protection Agency estimates that salt-induced road damage and vehicle corrosion cost $ 3 billion a year. That does not include damage to underground cables, which adds hundreds of millions to utility bills. Nor does it reflect the cost of brine leaking into porous water pipes, threatening the water supply. Salty water leaches into roadbeds, kills evergreens and poisons streams.

The various costs probably add another $ 2 billion to the national salt bill. Scientists estimate the full economic, or "life cycle," cost for a ton of salt at $ 500, or 20 times the $ 25 purchase price. That begins to make the switch to calcium magnesium acetate, perhaps the most promising alternative look practical. CMA, made from acetic acid and dolomitic(含白石的) lime, costs $ 600 a ton and has minimal adverse effect. Some researchers believe the cost can be halved by making CMA from waste cheese whey or pulp-mill effluent.

While CMA and other alternatives are being researched, many cities and states are cutting back on their use of salt. Keeping dispensing equipment in good repair helps reduce the amount spread.

Salt spread on road in winter may cause all the following problems except ______.

A．road damage

B．vehicle corrosion

C．damage of underground cables

D．car accident

"Salty" Rice Plant Boosts Harvests

British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their work may enable abandoned farms to become productive once more.

Tim Flowers and Tony Yeo, from Sussex University's School of Biological Sciences, have spent several years researching how crops, such as rice, could be made to grow in water that has become salty.

The pair have recently begun a three-year programme, funded by the Biotechnology and Biological Sciences Research Council, to establish which genes enable some plants to survive salty conditions. The aim is to breed this capability into crops, starting with rice.

It is estimated that each year more than 10m hectares(公顷) of agricultural land are lost because salt gets into the soil and stunts(妨碍生长) plants. The problem is caused by several factors. In the tropics, mangroves(红树林) that create swamps(沼泽) and traditionally formed barriers to sea water have been cut down. In the Mediterranean, a series of droughts have caused the water table to drop, allowing sea water to seep(渗透) in. In Latin America, irrigation often causes problems when water is evaporated(蒸发) by the heat, leaving salt deposits behind.

Excess salt then enters the plants and prevents them functioning normally. Heavy concentrations of minerals in the plants stop them drawing up the water they need to survive.

To overcome these problems, Flowers and Yeo decided to breed rice plants that take in very little slat and store what they do absorb in cells that do not affect the plants' growth. They have started to breed these characteristics into a new rice crop, but it will take about eight harvests before the resulting seeds are ready to be considered for commercial use.

Once the characteristics for surviving salty soil are known, Flowers and Yeo will try to breed the appropriate genes into all manners of crops and plants. Land that has been abandoned to nature will then be able to bloom again, providing much needed food in the poorer countries of the world.

Which of the following statements about Flowers and Yeo is true？

A．They are students at Sussex University.

B．They are rice breeders.

C．They are husband and wife.

D．They are colleagues at an institution of higher learning.

根据材料，回答题。

"Salty" Rice Plant Boosts Harvests

British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their work may enable abandoned farms to become productive once more.

Tim Flowers and Tony Yeo， from Sussex University"s School of Biological Sciences， have spent several years researching how crops， such as rice， could be made to grow in water that has become salty.

The pair have recently begun a three-year programme， funded by the Biotechnology and Bio logical Sciences Research Council， to establish which genes enable some plants to survive salty

conditions. The aim is to breed this capability into crops， starting with rice.

It is estimated that each year more than 10m hectares （公顷） of agricultural land are lost because salt gets into the soil and stunts （妨碍生长）plants. The problem is caused by several

factors. In the tropics， mangroves （红树林） that create swamps （沼泽） and traditionally formed barriers to sea water have been cut down. In the Mediterranean， a series of droughts have caused the water table to drop， allowing sea water to seep （渗透） in. In Latin America， irrigation often causes problems when water is evaporated （蒸发） by the heat， leaving salt deposits behind.

Excess salt then enters the plants and prevents them functioning normally. Heavy concentra-tions of minerals in the plants stop them drawing up the water they need to survive.

To overcome these problems， Flowers and Yeo decided to breed rice plants that take in very little salt and store what they do absorB．in cells that do not affect the plants" growth. They have started to breed .these characteristics into a new rice crop， but it will take about eight harvests before the resulting seeds are ready to be considered for commercial use.

Once the characteristics for surviving salty soil are known， Flowers and Yeo will try to breed the appropriate genes into all manners of crops and plants. Land that has been abandoned to nature will then be able to bloom again， providing much needed food in the poorer countries of the world.

Which of the following statements about Flowers and Yeo is true？ 查看材料

A.They are students at Sussex University.

B.They are rice breeders.

C.They are husband and wife.

D.They are colleagues"at an institution of higher learning.

"Salty" Rice Plant Boosts Harvests

British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their work may enable abandoned farms to become productive once more.

Tim Flowers and Tony Yeo, from Sussex University's School of Biological Sciences, have spent several years researching how crops, such as rice, could be made to grow in water that has become salty.

The pair has recently begun a three-year programme, funded by the Biotechnology and Biological Sciences Research Council, to establish which genes enable some plants to survive salty conditions. The aim is to breed this capability into crops, starting with rice.

It is estimated that each year more than 10m hectares (公顷) of agricultural land are lost because salt gets into the soil and stunts (妨碍生长) plants. The problem is caused by several factors. In the tropics, mangroves (红树林) that create swamps (沼泽) and traditionally formed barriers to sea water have been cut down. In the Mediterranean, a series of droughts have caused the water table to drop, allowing sea water to seep (渗透) in. In Latin America, irrigation often causes problems when water is evaporated (蒸发) by the heat, leaving salt deposits behind.

Excess salt then enters the plants and prevents them functioning normally. Heavy concentrations of minerals in the plants stop them drawing up the water they need to survive.

To overcome these problems, Flowers and Yeo decided to breed rice plants that take in very little slat and store what they do absorb in cells that do not affect the plants' growth. They have started to breed these characteristics into a new rice crop, but it will take about eight harvests before the resulting seeds are ready to be considered for commercial use.

Once the characteristics for surviving salty soil are known, Flowers and Yeo will try to breed the appropriate genes into all manners of crops and plants. Land that has been abandoned to nature will then be able to bloom again, providing much needed food in the poorer countries of the world.

Which of the following statements about Flowers and Yeo is true？

A．They are students at Sussex University.

B．They are rice breeders.

C．They are husband and wife.

D．They are colleagues at an institution of higher learning.

t is, urban【C1】______ have known for years that swaths of asphalt and concrete tend to【C2】______ the summer heat. As cities have grown,【C3】______ has the temperature problem. This summer, NASA and the Environmental Protection Agency teamed up with several U.S. cities to study urban "heat islands" and【C4】______ ways to bring some【C5】______ . The pilot program【C6】______ satellite, airplane and ground-based date to produce detailed maps of the hot and (comparatively) cool zones in the【C7】______ areas.

Images of Salt Lake City,【C8】______ in late July, document the【C9】______ of the urban heat problem. Some dark rooftops reach a temperature of 160 degrees F.(71 degrees C.). Jeff Luvall,【C10】______ heads the heat island project, notes that use of【C11】______ materials for roofs and parking lots would help【C12】______ solar heat upward. Urban forests also help reduce temperatures,【C13】 ______ the extent of the improvement depends on both the extent and arrangement of the forests. Luvall reports that【C14】______ along streams brings cool air into Salt Lake City; developers who turn these streams into concrete ditches throw away a【C15】______ natural air conditioning system.【C16】______ , scientists continue to fret about the broader, potentially【C17】______ more troublesome problem of global warming. Vice President Al Gore recently cited government data showing that the first half of 1998 was the warmest year【C18】______ record and called on Congress to adopt【C19】______ that would【C20】______ emissions of greenhouse gases.

【C1】

A．population

B．citizens

C．dwellers

D．people

根据下列文章,请回答 41～45 题。"Salty" Rice Plant Boosts Harvests

British scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their work may enable abandoned farms to become. productive once more.

Tim Flowers and Tony Yeo, from Sussex University's School of Biological Sciences, have spent several years researching how crops, such as rice, could be made to grow in water that has become salty.

The pair have recently begun a three-year programme, funded by the Biotechnology and Biological Sciences Research Council, to establish which genes enable some plams to survive salty conditions. The aim is to breed this capability into crops, starting with rice. It is estimated that each year more than 10m hectares (公顷) of agricultural land are lost because salt gets into the soil and stunts (妨碍生长) plants. The problem is caused by several factors. In the tropics, mangroves (红树林) that create swamps (沼泽) and traditionally formed barriers to sea water have been cut down. In the Mediterranean series of droughts have caused the water table to drop, allowing sea water to seep (渗透) in. In Latin America, irrigation often causes problems when water is oval)orated (蒸发) by the heat, leaving salt deposits behind.

Excess salt then enters the plants and prevents them functioning normally. Heavy concentrations of minerals in the plants stop them drawing up the water they need to survive.

To overcome these problems, Flowers and Yeo decided to breed rice plants that take in very little salt and store what they do absorb in cells that do not affect the plants' growth. They have started to breed these characteristics into a new rice crop, but it will take about eight harvests before the resulting seeds are ready to be considered for commercial use.

Once the characteristics for surviving salty, soil are known, Flowers and Yeo will try to breed the appropriate genes into all manners of crops and plants. Land that has been abandoned to nature will then be able to bloom again, providing much needed food in the poorer countries of the world.

第41题：Which of the following statements about Flowers and Yeo is true？

A．They are students at Sussex University.

B．They are rice breeders.

C．They are husband and wife.

D．They are colleagues at an institution of higher learning.