Battery-operated slippers are used ______ seeing in the dark.

A．to               B．as               C．by               D．for

根据对话内容，从方框内选出能填入空白处的最佳选项，其中有两项为多余选项。

A: Look at that strange thing, Wei Hua! What’s that?

B: It’s a key. 1.? ?????????

A: Our autobike (电动自行车)? 2.?

B: It was invented by my father. It’s a battery-operated（电池驱动的）machine.

A: ? 3.?

B: It’s used for riding or flying.

A: Flying? __4.____

B: You can just ride it like a autobike and it will fly as it goes faster enough.

A: ___5.___ I think your father is so great!

B: I think so. He has invented many things.

Electric bicycles which run on battery-operated (电瓶) motors are winning over riders of ordinary bikes   41 their speed, quality and environmental advantage.
They were first   42 on 1980s in China, but the selling was not very good. Today, thanks 43  improvements on battery quality, the electric bikes sell well. There are now more than 100 electric bicycle producers in China and 26 million such bicycles were produced in 2011. Japan is another large  44  of such bicycles in the world with a total production reaching 381,721in 2010.
  45 China is one of the largest producers of electric bicycles in the world, the   46  of its producers with mass production (大批量生产) is actually small.
Electric bicycles are still   47 in China. Time is needed for people to become familiar with them and accept them. Each bike’s price of between 2,000 yuan (US $318) and 3,000 yuan (US $477) is still  48  for ordinary citizens (民众). Although such bikes are quick, safe and 49 to operate, their batteries still have shortcomings (不足). They weigh more than 10 kilograms; their service life is   50  two years and they   51  400 yuan each.
There were more than 450 million bikes in China in 2006. If just one percent of all these bikes are replaced by electric  52  , the market will be very large. And   53  the battery is further improved and the price is    54   , many of us will not be able to keep back from    55  the latest electric bikes

Electric bicycles which run on battery-operated (电瓶) motors are winning over riders of ordinary bikes   41  their speed, quality and environmental advantage.

   They were first   42  on 1980s in China, but the selling was not very good. Today, thanks  43   improvements on battery quality, the electric bikes sell well. There are now more than 100 electric bicycle producers in China and 26 million such bicycles were produced in 2011. Japan is another large  44   of such bicycles in the world with a total production reaching 381,721in 2010.

      45  China is one of the largest producers of electric bicycles in the world, the   46   of its producers with mass production (大批量生产) is actually small.

Electric bicycles are still   47  in China. Time is needed for people to become familiar with them and accept them. Each bike’s price of between 2,000 yuan (US $318) and 3,000 yuan (US $477) is still   48   for ordinary citizens (民众). Although such bikes are quick, safe and  49  to operate, their batteries still have shortcomings (不足). They weigh more than 10 kilograms; their service life is   50   two years and they   51   400 yuan each.

There were more than 450 million bikes in China in 2006. If just one percent of all these bikes are replaced by electric  52   , the market will be very large. And   53   the battery is further improved and the price is    54    , many of us will not be able to keep back from    55   the latest electric bikes

1.A. because of   B. because   C. towards   D. at

2.A. build   B. built   C. building   D. to build

3.A. for  B. in   C. by   D. to

4.A. producer   B. production   C. produce   D. to produce

5.A. But   B. If    C. Although    D. When

6.A. buyer   B. number   C. price   D. owner     

7.A. old   B. tall   C. new    D. short

8.A. small   B. large   C. expensive   D. high

9.A. easy    B. difficult    C. hard    D. easily

10.A. other than  B. more than    C. over    D. less than

11.A. spend    B. cost    C. take    D. make

12.A. cars    B. bike    C. ones    D. one 

13.A. where     B. unless   C. whether    D. if

14.A. increased    B. raised    C. reduced    D. lifted

15.A. buying     B. brought    C. to buy     D. buy

Battery-operated slippers are used ______ seeing in the dark.