题目内容

________ from endless homework on weekends, the students now find their own activities, such as taking a ride together to watch the sunrise.

A．Freed B．Freeing C．To free D．Having freed

A

解析试题分析：考查分词做状语。本题的动词free摆脱…；使…免受…；与后面主语the students构成被动的关系，故使用过去分词在句中做状语。句意：在周末摆脱了无休止的家庭作业，学生们现在有了他们自己的活动，例如一起骑自行车去看日出。故A正确。
考点：考查分词做状语
点评：当分词做状语的时候，如果构成分词的动词与句子的主语构成主动关系，就使用现在分词做状语；当二者构成被动关系，使用过去分词做状语。如果分词的动作发生在谓语动词之前，就使用分词的完成式。如果分词与句子的主语没有关系，可以使用状语从句或者独立主格结构。

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____ from endless homework on weekends, the students now find their own activities, such as taking a ride together to watch the sunwise.

  A. Freed     B. Freeing     C. To free     D. having freed

____ from endless homework on weekends, the students now find their own activities, such as taking a ride together to watch the sunwise.

A、Freed    B、Freeing  C、To free  D、having freed

____ from endless homework on weekends, the students now find their own activities, such as taking a ride together to watch the sunrise.

A、Freed B、Freeing       C、To free        D、having freed

We learned that fossil fuels were formed before and during the time of the dinosaurs（恐龙）. We are using up the fuels. We can save fossil fuels by protecting and finding ways to use energy from “endless sources”, like the sun and the wind. Some people suggest that we should start using hydrogen（氢）.

Hydrogen is a colorless, smell-less gas that takes up 75 percent of the whole universe. Hydrogen is found on earth only in mixture with other elements such as oxygen, carbon and nitrogen. To use hydrogen, we must separate it from these other elements.

Hydrogen can be used in NASA’s space program as fuel for the spaceships, and in fuel cells that provide heat, electricity and drinking water for astronauts. Fuel cells are devices that directly change hydrogen into electricity. In the future, hydrogen could be used to fuel vehicles and aircraft and provide power for our homes and offices.

Hydrogen can be made from natural gas. An electrical current can also be used to separate water into its elements of oxygen and hydrogen. Some plants in the sea and bacteria（细菌） give off hydrogen through sunlight under certain conditions.

Hydrogen as a fuel is high in energy. Yet a machine that burns pure hydrogen produces almost zero pollution. NASA has used liquid hydrogen since the 1970s to drive rockets and spacecraft into orbit. Hydrogen fuel cells power the spacecraft’s electrical systems, producing clean by-product-pure water, which the crew drinks.

56. We can get hydrogen from the following EXCEPT ______ according to the passage.

A. natural gas    B. water                     C. creature in the sea          D. bacteria

57. Why could the hydrogen be used widely in the future?

A. Because it is of high quality.               

B. Because it has no pollution. 

C. Because it is easy to get it from all kinds of ways.      

D. Because there are much hydrogen existing in the universe.

58. The passage mainly tells us ________.

A. the usage of a new energy source        B. the future energy sources

C. a new energy source －hydrogen        D. how to get the energy source

       from endless homework on weekends, the stuclents now find their own activities to enjoy.

A．Freed

B．Freeing

C． To free

D．Having freed

 

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