题干

若抛物线上一点到其焦点的距离为,则点的坐标为(   )

A:

B:

C:

D:

上一题 下一题 0.0难度 选择题 更新时间:2014-04-09 12:49:16

答案(点此获取答案解析)

C

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阅读下面短文, 然后根据短文内容补全答题卡上对应表格中所缺失的信息,每空限1词。

    The "green" car has become popular in recent years. A green car is an environment friendly car. Today, most cars are powered (驱动) by petrol (汽油). They make our life easier. But cars have also made problems for the environment.

    There are a few new types of cars that use no petrol or a little petrol.

    Electric cars:This kind of car uses a battery (电池) for power. When you're not driving it, just plug it in like a mobile phone to power up the battery. They don't make exhaust (排放物). But car makers still can't make a battery that lasts for more than a few hours. That's why electric cars aren't very popular.

    Fuel cell cars (燃料电池车) : Fuel cell cars use hydrogen (氢) and oxygen (氧) to make power. The only exhaust they produce is clean water. But fuel cell cars are still much too expensive to make.

    Solar cars : This kind of car has large panels (板) on the top that take power from the sunshine. The car holds that power in a battery. Solar cars might be the cleanest of all. But no one uses them, because solar panels can't get enough power from the sun to make a car go for a long time. Also, they are very slow.

    Hybrid cars(油电混合车): This kind of car is the most exciting kind, because it is very clean and not too expensive. The hybrid car is very smart: Half the time, it uses petrol, and half the time it uses a battery. So, when the petrol engine is working, it puts some of its power back into the battery. It uses much less petrol than other cars. It also makes less pollution for the environment.

New types of

cars

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Problems

Electric cars

a ____

The battery doesn't last for more than a few hours.

Fuel cell car

hydrogen and oxygen

Fuel cell cars are much too ____to make.

Solar cars

____

Solar panels can't get enough power from the sun to make a car go for a long time. This type of car is too slow.

Hybrid cars

____and a battery

It makes less ____for the environment.