A carbon dioxide fire extinguisher has been partially discharged, and should be immediately （）.

A . Carbon dioxide is corrosive when exposed to fire B . Carbon dioxide should be applied slowly to a large engine room fire C . Its total cooling effect is far greater than water D . Its smothering effect is excellent for class B fire

A . first to the bottom of the flaming area，sweeping from side to side，and following the flames upward B . in a circular motion from the middle of the bulkhead outward C . to the top of the flaming area，sweeping from side to side，and working toward the bottom D . in an up-and-down motion from one side of the bulkhead to the other

A . where oil or chemical drums are stored B . in all battery storage locations C . in paint lockers D . in all of the above locatio

A . the "snow" which is sometimes discharged along with the gas is toxic B . prolonged exposure to high concentrations of C0 gas causes suffocation C . rapid dissipation of the C0 vapor D . the C0 gas is lighter than air and a large amount is required to extinguisha fire near the deck

A . greater range B . effectiveness on all types of fires C . cleanliness D . All of the above

A . 碳氢化合物 B . 碳氧化合物 C . 一氧化碳 D . 二氧化碳

A . flashing point B . combustion point C . auto-ignition point D . lower explosive limit

A . It causes minimal damage B . It is safer for personnel C . It is cheaper D . It is most effective on a per unit basi

A . lack of toxicity B . the multipurpose extinguishing ability C . burn-back protection D . cooling ability

A . at least annually B . whenever it is below its required weight C . only if the extinguisher has been used D . before every safety inspectio

A . at the base of the flames B . at the center of the flames C . to the lee side of the flames D . over the tops of the flame

A . persons in the space wear gas masks B . persons in the space wear damp cloths over their mouths and nostrils C . ventilation system is secured and all persons leave the space D . ventilation system is kept operating

A . greater range B . effective on all types of fires C . cleanliness D . All of the above

A . It causes minimal damage B . It is safe for personnel C . It is cheaper D . It is most effective on a per unit basi

A . Cleaner B . Effective C . Greater range D . More cooling effect

A . completely closing the compartment B . closing the compartment except for the ventilators C . leaving the compartment open to the air D . increasing the air flow to the compartment by blower

A . Effective even if ventilation is not shut down B . Will not deteriorate in storage C . Non-corrosive D . Effective on electrical equipment

A . Class "A" and class "B" B . Class "B" and class "C" C . Class "A" and class " C" D . Class "C", class "D", and class "E&quot

A . Alcohol foam B . Dry chemical C . Chemical foam D . Water fog

A.replaced in its proper location if weight loss is no more than 15% B.replaced in its proper location if weight loss is no more than 25% C.labeled empty and recharged as soon as possible D.labeled empty and replaced in its proper location regardless of weight

A．To illustrate methane's molecular structure. B．To show the link between global warming and smog. C．To suggest that fossil fuels should not be burned. D．To elaborate on a benefit of natural gas's cleanliness.

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.donate B.check C.withhold D.release