相关习题
 0  28310  28318  28324  28328  28334  28336  28340  28346  28348  28354  28360  28364  28366  28370  28376  28378  28384  28388  28390  28394  28396  28400  28402  28404  28405  28406  28408  28409  28410  28412  28414  28418  28420  28424  28426  28430  28436  28438  28444  28448  28450  28454  28460  28466  28468  28474  28478  28480  28486  28490  28496  28504  151629 

科目: 来源: 题型:

----Are you cold?

----No, __________.

A. at least         B. at most                C. never          D. at in the least

查看答案和解析>>

科目: 来源: 题型:

The teacher ____ the bottle dangerous..

A. said  B. told  C. looked   D. labeled

查看答案和解析>>

科目: 来源: 题型:

Our holiday plans are gradually________.

A. forming        B. figuring              C. shaping       D. getting

查看答案和解析>>

科目: 来源: 题型:

Everything is so expensive now.It is hardly ___ to save money.

A. probable   B. likely     C. possible     D. feasible

查看答案和解析>>

科目: 来源: 题型:

-----when has the country been open to international trade?

-----1978, I suppose.

A. Since      B. In         C. From               D. After

查看答案和解析>>

科目: 来源: 题型:

Unless ____ to speak,  you should remain silent at the conference.

A invited         B inviting           C being invited    D having invited

查看答案和解析>>

科目: 来源: 题型:阅读理解

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

查看答案和解析>>

科目: 来源: 题型:

—It’s a shame that Pearl hasn’t turned up yet.

—Look,_______.

A.he comes            B.here comes he   C.is he coming              D.here he comes

查看答案和解析>>

科目: 来源: 题型:

Can you imagine_______such a mean person?

A.she marrying                                                B.her to marry

C.her marrying                                                D.that her marrying

查看答案和解析>>

科目: 来源: 题型:

He is a ___ friend of mine.

A. close   B. silent   C. quiet    D. near

查看答案和解析>>

同步练习册答案