When a handheld video game runs out of power,all you have to do is plug it in and charge it  up.Within a few years,some of you might do the same thing with mom's car.Automobile companies are developing vehicles that will plugin to electric sockets  ,just like many laptops,digital cameras,cellphones and small video game players do.Called "plugin hybrids  ",these cars will get most of their power from electricity.Their drivers will rarely have to stop at gas stations. The technology is more than just cool.In our automobilefilled world,plugin vehicles could reduce the amount of gasoline we use.That gas is made from crude oil  ,which keeps rising in cost.Plus,driving around in these hybrids may even help the environment.Gasburning cars produce a lot of carbon dioxide,a type of greenhouse gas.These gases stay in the atmosphere,where they trap   heat and cause global warming. The first companyproduced plugin hybrids could hit the roads by 2010.But engineers still have a lot of work to do to make the technology practical and inexpensive. Batteries are the biggest challenge.In the pluginhybrid world,lithiumion   (Liion) batteries are getting the most attention.These batteries can store a large amount of energy in a small package,and they last a  ly long time between charges.Liion batteries are standard in laptops,cellphones,heart devices and other similar portable   devices. But because cars are so big and heavy,it would still require a suitcasesized Liion battery to power about 12km of driving.What's more,the batteries are extremely expensive. "A car filled with batteries could go a long distance," says Ted Bohn,an electrical engineer in Chicago."But it couldn't haul   any people,and it would cost $100,000." So researchers need to figure out how to make batteries smaller and cheaper,among other questions. "The answers don't exist yet," Bohn says."As a kid I thought someone someplace knows the answer to everything.All of these questions haven't been decided.That's what engineering is about--making a guess,running tests and finetuning   results." The passage mainly talks about  _      of a new car.
the batteries the speed the developing the appearance
Question: When a handheld video game runs out of power,all you have to do is plug it in and charge it  up.Within a few years,some of you might do the same thing with mom's car.Automobile companies are developing vehicles that will plugin to electric sockets  ,just like many laptops,digital cameras,cellphones and small video game players do.Called "plugin hybrids  ",these cars will get most of their power from electricity.Their drivers will rarely have to stop at gas stations. The technology is more than just cool.In our automobilefilled world,plugin vehicles could reduce the amount of gasoline we use.That gas is made from crude oil  ,which keeps rising in cost.Plus,driving around in these hybrids may even help the environment.Gasburning cars produce a lot of carbon dioxide,a type of greenhouse gas.These gases stay in the atmosphere,where they trap   heat and cause global warming. The first companyproduced plugin hybrids could hit the roads by 2010.But engineers still have a lot of work to do to make the technology practical and inexpensive. Batteries are the biggest challenge.In the pluginhybrid world,lithiumion   (Liion) batteries are getting the most attention.These batteries can store a large amount of energy in a small package,and they last a  ly long time between charges.Liion batteries are standard in laptops,cellphones,heart devices and other similar portable   devices. But because cars are so big and heavy,it would still require a suitcasesized Liion battery to power about 12km of driving.What's more,the batteries are extremely expensive. "A car filled with batteries could go a long distance," says Ted Bohn,an electrical engineer in Chicago."But it couldn't haul   any people,and it would cost $100,000." So researchers need to figure out how to make batteries smaller and cheaper,among other questions. "The answers don't exist yet," Bohn says."As a kid I thought someone someplace knows the answer to everything.All of these questions haven't been decided.That's what engineering is about--making a guess,running tests and finetuning   results." The passage mainly talks about  _      of a new car.
A. the batteries
B. the speed
C. the developing
D. the appearance
Answer: