[单项选择]When will President Bush leave for his 5-day African tour.’

[单项选择]When will President Bush leave for his 5-day African tour

[单项选择] When George W Bush delivered his State of the Union Address this past January, three words appeared that had not previously been heard from the Oval Office: Switchgrass, stalks and woodchips. Bush’’s signals on renewable energy have been decidedly mixed. Shortly before he visited the National Renewable Energy Laboratory (NREL) in Colorado last February, a $5 million funding shortfall forced the lab to lay off 32 workers. Bush blamed the layoffs, and NREL got its funding back. Switchgrass is a fast-growing perennial plant native to the central and eastern U.S. and tolerant of many different soil types. To make cellulosic ethanol, switchgrass — or any cellulose-based plant — is broken down to make sugar, then fermented to make the fuel. Supporters say that when blended with petroleum products, ethanol from switchgrass results in a net energy gain of 334 percent, compared to just 21 percent for corn-based ethanol. The cellulosic process has been invented and is being re
A. switchgrass is the most ideal raw material for the cellulosic ethanol production
B. corn-based ethanol has higher energy rate than switchgrass-based ethanol
C. corn-based ethanol has been invented and is being refined, but not commericalized
D. switchgrass is directly used as raw material for the cellulosic ethanol production