题目内容：

It encouraged us to visit Quora.com, the online question and answer community, to find out how users get the most out of every tank of gas.

Light makes right

Alex Elderfield noted that excess weight prevents an engine from burning fuel efficiently. "Only carry what is essential in your car, clean out any junk or necessary items otherwise you are paying for the fuel to cart these from place to place," he wrote.

Driving smoothly — that is, not mashing the gas and then slamming the brakes later down the road — was a fixture of many responses. Quora user Clint Law agreed on that advice, who wrote, "Every little bit of kinetic energy that your brakes lose, your engine burned in fuel to build up." Overbraking should consequently be viewed as wasted acceleration. "That's really what kills your fuel economy," he argued.

Keep the pressure up

Keeping the recommended tire pressure for your car was another mantra among Quora users. Marlyn Rosent said she checked her tire pressure every time she filled up her SUV. Quora user Doug Dingus checks his tire pressure every weekend. “Less tire contact means reduced rubbing, requiring less fuel,” he said.

Air conditioning or windows

Though the summer heat get many drivers to roll up the windows and turn on the air conditioning, some people argued that running the A/C wastes too much gas. In between were many shades of grey.

Achilleas Vortselas said it would depend largely on a car’s speed. He wrote that as a general rule, people should drive with the windows down around the city and turn the air conditioning on when hitting the highway, where a car’s aerodynamic(空气动力的) characteristics would be influenced by opened windows.

More seriously minded people, however, said to travel as much as possible with windows up and the A/C off. Eddie Xue gets by with just a wisp of outside air. “Use the fan and open your windows every now and then at lower speeds," he wrote.

1.What can we learn from what Clint Law wrote?

A. Overbraking is a waste of gas.

B. Carry what we need in the car.

C. Build up energy to drive smoothly.

D. Stepping on the gas freely can keep a balance.

2.What do we know from Doug Dingus’ words?

A. Checking tire pressure will require less fuel.

B. Filling up the SUV leads to reduced rubbing.

C. Keeping the recommended tire pressure is necessary.

D. Braking fiercely can keep wasting acceleration.

3.The author says “In between were many shades of grey” to indicate that ________.

A. rolling up the windows and turning on the air conditioning waste too much gas

B. people should try their best to travel with windows up and the A/C off

C. when a car approaches higher speeds, the A/C should come on

D. there’s balance between the air conditioning and windows usage

4.Which is the suitable title of the passage?

A. Fuel efficiency, straight from source

B. Driving with the windows down and using the A/C

C. How to save at the pump this summer

D. Reducing the weight and increasing the vehicle’s fuel economy