Gas turbines differ from steam turbines in that （）.

A . portable ventilation system B . flame safety lamp C . self-contained breathing apparatus D . gas mask

A . Exhaust gas pressure from the stack B . High capacity fan C . Inert gas compressor D . Natural aspiratio

A . intercooler B . compressor C . cylinder D . open air

A . the oil separator B . the fresh water generator C . the compressor D . fire pum

A . starting air bottles B . diesel engines C . boilers D . refrigeration compressor

A . to give off；which B . giving off；which C . to give off；that D . giving off；that

A . whenever B . however C . wherever D . whether

A . 正确 B . 错误

A . compass error B . true heading C . variation D . deviatio

A．exploration B．achievement C．interaction D．nurturing

A．exploration B．achievement C．interaction D．nurturing

A．the former is predictable while the latter is not． B．the former is specific while the latter is not． C．the former is a formalized process while the latter is not． D．the former is more open—ended and all-inclusive．than the latter．

A．put out B．put off C．put forth D．put down

The first study was done at Duke University in Durham, North Carolina. Researchers pumped extra carbon dioxide into a test area where pine trees were growing. The trees grew thirty-four percent faster during the first three years. However, in time, the trees slowed to about their normal growth rate. The scientists say this is because trees need other nutrients, such as nitrogen. In the second study, researchers from Duke and Bowdoin College in Brunswick, Maine examined the soil around trees. They discovered that as the leaves broke down into the soil, all the carbon was not trapped in the soil. Much of it was released into the atmosphere as carbon dioxide. The findings of the two studies were published last month in Nature magazine. They suggest there is limited value in planting trees to reduce the carbon dioxide pollution in the atmosphere. Forest planting has been a part of negotiations on a world agreement to reduce greenhouse gases that scientists believe cause global warming. The United States, Canada, Japan and some other industrial countries have supported the idea. But this new research suggests the idea is not as effective as environmental activists had thought. Scientist Ram Oren of Duke University led the study on tree growth. He says that earlier estimates on the ability of forests to absorb carbon dioxide were overly hopeful. Some scientists not involved in the studies say the research provides some of the first evidence on how trees react to carbon dioxide. Other scientists say the research disputes a belief among some coal and power companies. The companies say that rising levels of carbon dioxide in the atmosphere will not create harmful global warming. Instead, they say it will increase forests and other plants. What is the purpose of this passage？ A．Introduce some new ideas about the relationship between trees and carbon dioxide. B．Introduce recent condition of global industrial pollution. C．Call on people to plant more trees to reduce greenhouse gases. D．Point out that power companies should be responsible for the rising levels of carbon dioxide.

A．seek federal contracts to provide marketsfor minority businesses B．encourage minority businesses to provide markets for other minority businesses C．attempt to maintain a specified rate of growth in the minority business sector D．rely on the participation of large corporations to finance minority businesses E．select minority businesses on the basis of their location

A．化学溶剂法Chemical solvent method B．物理溶剂法Physical solvent method C．直接转化法Direct conversion D．干式床层法Dry bed method