More than half the world's population live in cities,and by 2050 the UN expects that proportion to reach 68%. This means more homes, roads and other infrastructure. In India alone, a city the size of Chicago will have to be developed every year to meet demand for housing. Such a construction increase is a bad sign for dealing with climate change, because making steel and concrete, two of the most common building materials, generates around 8% of the world's CO2 emissions （排放）. If cities are to expand and become greener at the same time, they will have to be made from something else.
Wood is one of the most promising sustainable （可持续的）alternatives to steel and concrete. It is not,however, everyday wood that is attracting the interest of architects.
Rather, it is a material called engineered timber. This is a combination of different layers, each designed to meet the requirements of specific parts such as floors, panels and beams（横梁）. Designers can use it to provide levels of strength like steel, in a product that is up to 80% lighter. In addition, engineered timber is usually made into large sections in a factory for future use, which reduces the number of deliveries to a construction site.
According to Michael Ramage of the University of Cambridge,a wooden building produces 75% less CO2 than a steel and concrete one of the same size. However,if building with wood takes off， it does raise concern about there being enough trees to go round. But with sustainably managed forests that should not be a problem, says Dr Ramage. A family-sized apartment requires about 30 cubic metres of timber,and he estimates Europe's sustainable forests alone grow that amount every seven seconds. Nor is fire a risk, for engineered timber does not burn easily. Besides, fireproofing layers can be added to the timber. All in all, then, it looks as if wood as a building material may get a new lease of life.



Why is India mentioned in paragraph 1？ ______

A. To point out the severe pollution.
B. To predict the population increase.
C. To indicate the high degree of urbanization.
D. To show the great need for building materials.

What can be learned about engineered timber？ ______

A. It is produced at a low cost.
B. It hardly appeals to architects.
C. It helps save energy in transportation.
D. It possesses greater strength than steel.

What does the underlined phrase "takes off" in the last paragraph mean？ ______

A. Becomes cheaper.
B. Gains popularity.
C. Requires less work.
D. Proves sustainable.

What can be a suitable title for the text？ ______

A. Making Future Cities More Attractive
B. Living in a World with Less Emission
C. Building Sustainable Cities with Woods
D. Growing More Trees for Future Building