TPO防水卷材产品规格：卷材厚度有（）和（）两种规格。卷材宽度有（）米不等。长度有1

外伤性颅内血肿的主要致命因素是（）。

A.急性脑疝

B.弥漫性脑水肿

C.昏迷所致肺部感染

D.脑脊液循环受阻

E.蛛网膜下腔出血

All too often , a choice that seems sustainable（可持续的）turns out on closer examination to be problematic. Probably the best example is the rush to produce ethanol（乙醇）for fuel from corn . Corn is a renewable resource —you can harvest it and grow more, almost limitlessly. So replacing gas with corn ethanol seems like a great idea.

One might get a bit more energy out of the ethanol than that used to make it, which could still make ethanol more sustainable than gas generally, but that’s not the end of the problem. Using corn to make ethanol means less corn is left to feed animals and people, which drives up the cost of food. That result leads to turning the fallow land — including, in some cases, rain forest in places such as Brazil — into farmland, which in turn gives off lots of carbon dioxide（CO2）into the air. Finally, over many years, the energy benefit from burning ethanol would make up for the forest loss. But by then, climate change would have progressed so far that it might not help.

You cannot really declare any practice “sustainable” until you have done a complete lift-cycle analysis of its environmental（环境的）costs. Even then, technology and public policy keep developing, and that development can lead to unforeseen and undesired results. The admirable goal of living sustainable requires plenty of thought on an ongoing basis.

小题1:What might directly cause the loss of the forest according to the text?

A．The growing demand for energy to make ethanol.

B．The increasing carbon dioxide in the air.

C．The greater need for farmland.

D．The big change in weather.小题2:The underline word “it” in the second paragraph refers to

A．the energy benefit

B．the forest loss

C．climate change

D．burning ethanol小题3:The author thinks that replacing gas with corn ethanol is    

A．impractical

B．acceptable

C．admirable

D．useless小题4:What does the author mainly discuss in the text?

A．Technology.

B．Sustainability.

C．Ethanol energy.

D．Environmental protection.

大型给水泵均设有暖泵装置。

试分析喷油提前角对柴油机的燃烧过程有何影响？