48． Who suffer the breathing problems most according to the latest study?
49． The researchers decided to study the effects on breathing first
because might appear in a later period of time.
50. are sharply criticized by some lawmakers because they let workers labor at Ground Zero without satisfactory equipment.
51. What measures have the officials promised to take to deal with the health problem?
Section B
Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statement. For each of them there are four choices marked A), B), C), and D). You should decide on the best choice and mark the corresponding letter on Answer Sheet 2 with a single line through the centre.
Passage One
Questions 52 to 56 are based on the following passage.
With the prospect of coal and petroleum supplies running out and with air pollution becoming an increasing concern, the major countries of the world are seeking alternate sources of energy. If a means to obtain energy from water, especially from the ocean, can be effected economically, it would provide a neverending supply of energy, since 70% of the earth’s surface is ocean and another 10% is fresh water in rivers and lakes.
From the beginning of time man has used waterpower as a source of working energy—waterfalls and dams—but these are fresh water sources and are landlocked. The seas have contributed little or nothing in the way of power. The use of temperature variation between currents is one area of exploration. Ocean water is heated by the sun near the equator and drawn by the rotation of the earth toward the poles, where it cools and drops toward the ocean floor and starts its journey back toward the equator. The differential between the two currents is 1℃ and 7℃. To use it, the scientists must find the places where they run near land and are not too far away from each other.
America, the greatest consumer of energy, has been working on another kind of thermal sea energy proposal. One plan would somewhat resemble the operation of a refrigerator on a vast scale. Warm water would be the heat source, cold water the heat sink. A component such as fog would be liquid at a cold temperature and turn to gas as it warmed.
Oceans also offer wave power, tides and the chemical reaction of salt water as potential sources of energy. All these uses are theoretically possible. Britain is interested in wave power, using a string of “tear drop” devices that depend on very active wave areas at 100 feet depths. In addition to this, the British are working on a method that the Japanese have already put into practical use on a small scale for powering their navigational boats. This method is called an oscillating(振荡) water column and rides the waves with a series of cylinders(气缸) having oneway air valves. Wave movement produces air under pressure that has only one escape route—to a turbine(涡轮) that powers a generator.
