This morning, a Virgin Atantin 747 Jumbo Jet became the first commercial airplane to fly o

This morning, a Virgin Atantin 747 Jumbo Jet became the first mercial airplane to fly on biofuel. The short flight from London to Amsterdam used a blend of 20% babassu(棕榈) oil mixed with 80% conventional jet fuel.
What was really exciting about the flight was the fact that the engine did not have to be altered in any way for the biofuel to work While this is a great initial step in trying to reduce CO2(carbon-dioxide)emissions(排放)from airplanes. there are a lot of hurdles (障碍)that still need to be overe.
First and foremost, unlike the normal fuel used to run airplanes (known as Jet A),biofuel freezes at high altitudes. Also, Jet‘A’fuel burns consistently (at the same pace),which means it provides a safe and reliable fuel for long flights--engineers are not sure if biofuel will be able to do the same.
The biggest hurdle to a full biofuel switch is our ability to be able to grow enough crops that can be converted to biofuel. There are two concerns that scientists have in this matter – the first is that the land to grow the extra crops will e from clearing more of our forests and the second is that since it petes with what we eat, the price of food will go up.
However, Richard Branson of Virgin Airlines, envisions that if biofuel starts to replace oil on a greater basis, it will be manufactured from algae（藻类）produced in sewage treatment plants, not from food sources.
Birgin Airlines is not the only one trying to look for alternative fuel sources. Earlier this year, an Airbus A380 used another alternative fuel－a man-made mix of gas-to-liquid, in one of its four engines. The flight was tested by Rolls Royce (manufacturer of jet engines), in partnership with Shell (an oil pany). Rolls Royce is also working with Air New Zealand on a similar project.
While a plete switch to alternative fuel may take years, it is very encouraging to see airlines, oil panies and airplane manufacturers all ing together to try to make it happen!
【小题1】．Why does Virgin Airlines try to replace normal fuel with biofuel?A．To cut down the flight cost of the pany.B．To remove some hurdles for the biofuel to work.C．To reduce CO2 emissions from airplanes.D．To test plane engines on biofuel.【小题2】．Which is NOT true for a full biofuel switch of airplanes?
A Biofuel cannot run for long flights.                  
B．Biofuel cannot work at high altitudes.
C．Man has not enough land to grow extra crops for biofuel. 
D．It’s not easy for sewage treatment plants to manufacture biofuel.
【小题3】．One of the hurdles to be overe for a full biofuel switch is to    .A．alter the engine for airplanesB．make biofuel burn consistentlyC．open more land to grow more cropsD．develop sewage treatment plants【小题4】．We can infer from the last paragraph that    .A．there is a long way to go for a plete switch to alternative fuelB．it won’t be long before alternative fuel es into useC．airlines, oil panies and airplane manufacturers are reliableD．alternative fuel has a bright future【小题5】．Which of the following can best serves as the title of this passage?A．Biofuel-Alternative Fuel Sources.B．The First Commercial Flight Powered by Biofuel.C．How to Reduce CO2 Emissions from Airplanes.D．Vigin Airlines Trying to Alter Fuel Sources.C