17. ________ the grandparents love the children, they are strict with them.

A. While   B. As    C. Since         D. Because

Though “nanometer” is now a fashionable term all over the world,few people know exactly what it is.It has become a new favorite of manufacturers and sellers in recent years.Many “high-tech” products bearing the name “nano” have entered the market,bringing more mysterious feeling to surprised consumers.

Nanometer is a very small length unit of measure,and is very small.One millimeter is 1000 micrometers,and one micrometer is 1000 nanometers.That is,one nanometer is one billionth of a meter.Nano materials are solid materials composed of particles or crystallites of less than 100 nanometer in size.Then,is a cup made of nano material really any different from an ordinary cup in function as far as how it works?

Are nano cups really so wonderful?A reporter went to the Institute of Nanomedicine,which is the first such institute of such a sort in the world and the only one in China,specializing in researching the investigation  of the application of nano technology into medicine.

Ji(director Institute of Nanomedicine):

A water molecule is composed of 2 hydrogen atoms and 1 oxygen atom.It can be alterchanged only by special manipulation of the atoms.The material constituting the cup can have a nanometer particles size of the nano level.But it cannot change the chemical and physical properties of the water contained in it.The water in the cup is still water.When people drink it,it will produce no special effect on human body.

Prof.Ji told the reporter,so far,the investigation of nano materials is still confined in the laboratory.No commercial micro products can be produced yet.With the present level of science and technology,the time of everyday goods age of daily use articles made of nanometer materials is still years away.

The commodities labeled with nano marks in the market now are only traditional products coated with a thin layer of nanometer material,which makes them more abrasion resistant,much easier to be cleaned,or oil repelling or moth proof.

Prof.Ji explained that nano cup is a real cup.It can also be included in the list of nano products in a certain sense.But the nano cup has not changed its property and function as a cup.It is not a magical medicine for curing and health care.

Which of the following shows the right relationship?

A.nanometer<millimeter<micrometer<meter

B.nanometer<micrometer<millimeter<meter

C.micrometer<millimeter<nanometer<meter

D.millimeter<micrometer<nanometer<meter

The underlined part in the last second paragraph but one is about_________.

A.the strong points of nano cups                        B.the shortcomings of nano cups

C.the uses of nano cups                                     D.the wonders of nano cups

Which of the following does not show that nano cups are different from ordinary cups?

A.Nano cups can’t make people healthier.

B.Nano cups are made of a different material.

C.Nano cups are much easier to be cleaned.

D.Nano cups are hard to produce.

According to the text,nano cups in the market are_________.

A.only traditional products

B.ordinary cups covered with a little nanometer material on the surface

C.cups made of a nano material

D.cups made of a mixed material

“I love traveling. I hope to go with you this time.” “But does your mother _____ you to go？”

    A. let          B. agree

    C. allow        D. promise

Though I have often heard this song _______. I have never heard you _______ it.

A. being sung, sang       B. sang, singing

C. sung, sing   D. to be sung, to sing

I would love _______ to the party last night but I had to work extra hours to finish a report.

A. to go  B. to have gone

C. going  D. having gone

The earth's biosphere (the surface layer of the planet and the surrounding atmosphere) provides the land, air, water, and energy necessary to sustain life. This life-support system is a complex, interdependent one in which energy from the sun is changed into food for humans. The entire system depends on the sun, reasonably moderate temperature, and enough supplies of oxygen, pure water, and fertile soil.

Since the earth's creation millions of years ago, the ecosystem has worked as an interdependent system relatively undisturbed by outside forces. But recently, especially since the Industrial Revolution, human beings have begun to disturb the balance of nature. Natural resources have been severely depleted (消耗) (forests have been destroyed, fertile land worn away, water polluted, and minerals used up), and the life-support system of air, water, and land has been poisoned by a variety of waste products and chemicals.

The degree of these problems was noted in a report by the U.N. Developing Council on Environmental Quality. This report predicted that if present trends continue, the world will be more crowded and polluted and less stable ecologically and politically than the world we live in now.

The twin problems of resource shortages and pollution are caused by three social forces.  First, the tremendous increase in population growth constantly increases the demand for food, energy, and other products. As the current population continues to increase, the stress on an already overburdened environment will be increased．A second source of the problem is the concentration of people in urban areas, where the ecosystem simply cannot absorb their waste products. Finally, environmental problems are worsened as more and more nations move toward modem development: an increased reliance on modern technology. As these nations become more technological, they will consume more energy, deplete more natural resources, and create more waste products than the biosphere can absorb.

The life-support system is composed of _____.

       A．a(chǎn)ir, water and land   B．the earth, the sun and energy

       C．food, land and energy     D．food, energy and the sun

The life-support system _____.

       A．change energy from the sun into food for humans

       B．depends on the sun for enough supplies of air, water and land

       C．exists in the surface layer of the earth and the surrounding atmosphere

       D．is a complex but independent system

The life-support system has been badly damaged by _____.

       A．natural forces   B．human activities  C．social movements      D．political changes

The passage mainly talks about _____.

       A．the effects of Industrial Revolution on human beings

       B．the importance of life-support system to human beings

       C．the significance of balance of nature

       D．the destruction of life-support system and its causes

________ twice, the postman refused to deliver our letters unless we chained our dog.

A. Being bitten      B. Bitten

C. Having bitten     D. To be bitten

Very few experts have ____ with complete new answers to the world s economic problems.

A. come down    B. come around  C. come up   D. come to

The first textbooks written for teaching English as a foreign language ____ in the 16th century.

A. came about  B. came out     C. came along  D. came up

---I'm hungry, what's for the supper? ____

---I haven't, actually I've just made a large salad, but there's loaf of fresh bread if you want to.

A. Why is supper not ready now?     B. Let's go out for dinner.

C.I hope you've made plenty of chips.  D.We had a good dinner yesterday.