58.
The
advertisement is made believable by ___
A. telling
stories B.
using figures
C. making
comparisons D. asking
questions
C
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(汽车)companies are
developing vehicles that will plug in to electric sockets(插座), just like many
laptops, digital cameras, cellphones and small video
game players do. Called "plug-in hybrids(混合动力车)", 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 automobile-filled world, plug-in
vehicles could reduce the amount of gasoline we use. That gas is made from
crude oil(原油), which keeps rising in cost. Plus, driving around in these
hybrids may even help the environment. Gas-burning 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 company-produced plug-in 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 plug-in-hybrid world, lithium-ion(锂离子)(Li-ion)batteries are
getting the most attention. These batteries can store a large amount of energy
in a small package, and they last a relatively long time between charges. Li-ion
batteries are standard in laptops, cellphones, heart
devices and other similar portable(便携的)devices.
But
because cars are so big and heavy, it would still require a suitcase-sized
Li-ion 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(拖拉)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
fine-tuning(微调)results. "
