题目内容：

    Buildings can become greener. They can use more recycled steel and can be built in off-site factories，greatly reducing lorry journeys. But no other building material has environmental credentials（认证）as exciting and overlooked as wood.

The energy required to produce a laminated（复合的）wooden beam is one-sixth of that required for a steel one of comparable strength. As trees take carbon out of the atmosphere when growing，wooden buildings contribute to negative emissions by storing the stuff. When a mature tree is cut down，a new one can be planted to replace it，capturing more carbon. After buildings are pulled down，old beams and panels are easy to recycle into new structures. And for improving older buildings to be more energy efficient，wood is a good insulator（绝缘体），A softwood window frame provides nearly 400 times as much insulation as a plain steel one of the same thickness and over a thousand times as much as an aluminium one.

A race is on to build the world's tallest fully wooden skyscraper. But such buildings are still uncommon. Industry disunity，cut-throat competition for contracts and low profit margins（差额）mean that most building firms have little money for greener construction methods beyond what regulation requires

Governments can help urge the industry to use more wood，particularly in the public section. That would help wood-building specialists achieve greater scale and lower costs. Zero-carbon building regulations should be changed to take account of the emissions that exist in materials. This would favour wood as well as novel ways of producing other materials.

Construction codes could be adjusted to make building with wood easier. Here the direction of travel is wrong. Britain，for instance，is banning the use of wood on the outside of tall buildings after 72 people died in a tower fire in London in 2017.That is a nonsense. Grenfell Tower was covered in aluminium and plastic，not wood. Modern cross-laminated wood panels perform better in fire tests than steel ones do.

Carpentry alone will not bring the environmental cost of the world's buildings into line.

1.What's the text mainly about?

A.Wood is the first choice for green buildings.

B.The public section makes good use of wood.

C.Building companies cannot afford greener construction.

D.Steel can reduce the environmental costs of buildings.

2.What does Paragraph 2 focus on?

A.Origins of wood structures.

B.Advantages of wood for building.

C.Reasons for green window frames.

D.Differences between steel and wood

3.Which of the following will discourage greener construction?

A.The races of wooden skyscrapers. B.Strict regulations on materials.

C.The push of the government. D.Fierce industry competition.

4.What can be inferred from the text?

A.Wood is to blame for a big building fire.

B.Britain will lift the ban of using wood on the outside wall.

C.Building with wood is facing an unfavorable situation.

D.The environmental costs of buildings rely on carpentry.