单选题Fires involving combustible metals are classified as （）.A class A firesB class B firesC class C firesD class D fires

A petroleum liquid has a flash point of 85°F. This is a grade ______.

A.B flammable liquid

B.C flammable liquid

C.D combustible liquid

D.E combustible liquid

Camphor oil is classified as a ______．

A.Grade A flammable liquid

B.Grade C flammable liquid

C.Grade D combustible liquid

D.Grade E combustible liquid

The Smokey Bear(护林熊) fire prevention program has resulted in a savings of $20 billion on all federal(联邦的), state and private forested land(私有林地). In 1941, 208,000 forest fires burned 30 million acres, while in 1981, fewer than 165,000 fires burned about three million acres. While forest usage has increased, the proportion(比例) of human-caused fires has remained stable; people still cause nine out of ten forest fires. But the biggest cause of fires is arson(纵火), accounting for(引起) 34 percent of forest fires in 1981.

1. According to the passage, use of forested land has ____.

A、stabilized

B、been privatized

C、decreased

D、risen

2. According to the passage, in 1941 forest fires burned ____.

A、less acres than in 1981

B、3 million acres

C、ten times as many acres as in 1981

D、20 million acres more than in 1981

3. According to the passage, the number of human-caused fires ____.

A、has remained the same proportionately

B、has increased

C、is the same as the arson cases

D、accounts for 34 per cent of forest fires

4. According to the passage, which of the following statements is true?

A、Nine out of ten fires are caused by arsonists.

B、The Smokey Bear program has saved the nation a lot of money.

C、There are more forest fires now than before.

D、People do not use the forests as much as they did in the past.

5. It may be inferred from the passage that ____.

A、the majority of fires are caused by humans

B、arson is increasing every year

C、more acres are destroyed by fire each year

D、fewer people are using the forests

Combustible gas indicators measure the presence of combustible gas as a percentage of the____.

A.flash point

B.upper explosive limit

C.lower explosive limit

D.fire point

A foam-type portable fire extinguisher is most useful in fighting a fire in ______.

A.generators

B.oil drums

C.the bridge controls

D.combustible metals

What is the best instrument for establishing a safe working area before welding in a confined space?

A.An oxygen indicator

B.A combustible gas indicator

C.A combination combustible gas and oxygen indicator

D.A flame safety lamp

What is classified as a combustible liquid ________．

A.Acetaldehyde

B.Ethyl alcohol

C.Carbon tetrachloride

D.Tetramethylene glycol

A fire involving trash and paper waste would be classified as a ______.

A.class A

B.class B

C.class C

D.class D

A portable foam (stored-pressure type) fire extinguisher would be most useful in combating a fire in ______.

A.generators

B.oil drums

C.the bridge controls

D.combustible metals

Foam-type portable fire extinguishers are most useful in combating fires involving ______.

A.solid materials such as wood or bales of fiber

B.inflammable liquids

C.electrical equipment

D.metallic solids