At Watson Bar Creek, a brook six thousand feet high in the mountains of British Columbia, Canada,a mineral search group gathered bags of tree seeds. Boxed were filled with small banches from te trees. Roots were dug and put into boxes. Each bag and box was carefully marked. In a scientific laboratory the parts of the forest trees were burned to ashes and tested .Each small part was examined to learn whether there were minerals in it.
Study of the roots , branches,and seeds showed no silver. But there were small amounts of gold in the roots and a little less gold in the branches and seeds. The seeds growing nearest to the tree trunk had more gold than those growing on the ends of the branches.
If the trees had not indicated that there was gold in the ground, the scientists would not have spent money to pay for digging into the deeper. They did dig and found more fold below. They dug deeper. They found large quantities of gold.
1.Scientists were flying over a desert or hilly wasteland or a mountain region in order to search for _____ in the ground. a.gold b.silver c.metals d.minerals
2.The study of trees,branches and roots indicates that_______.
a.there were larger amounts of gold in the branches than in the seeds. b.there were small amounts of gold in the roots than in the branches c.there were larger amounts of gold in the seeds growing nearest to the tree trunk than seeds growing on the ends of branches. d.there were more gold in the branches than in the roots
3.Which is the best title ?
a.Scientists searching for metals with sepcial power b.New methods of searching for minerals c.Gold could be found by trees and plants
d.A new method of searching for minerals---using trees and plants
4.Which of the following is not mentioned as part of a tree that can help find minerals? a.leaves
b.roots c.branches d.seeds
5.The scientists were searching for minerals by using ______. a.X-ray b.magic power c.a special instrument d.trained eyes
第21篇答案：dcdad
第22篇
In the United States, it is not customary to telephone somenone very early in the morning. If you telephone him early in the day, while he is shaving or having breakfast, the time of the call shows that the matter is very important and requires immediate attention.The same meaning is attached to telephone calls made after 11:00 p.m..If someone receives a call during sleeping hours , he assumes it's a matter of life or death. The time chosen for the call communicates its importance.
In social life, time plays a very important part. In the U.S.A. guests tend to feel they are not highly regarded if the invitation to a dinner party is extended only three or four days before the party date. But it is not true in all countries. In other areas of the world , it may be considered foolish to make an appointment too far in advance because plans which are made for a date more than a week away tend to be forgotten. The meaning of thime differs in different parts of the world. Thus, misunderstandings arise between peopel from cultures that treat time differently. Promptness is valued highly in American life, for edample. If people are not prompt, they may be regarded as impolite or not fully responsible. In the U.S. no noe would think of keeping a business associate waiting for an hour , it would be too impolite . A person who is 5 minutes late, he will say a few words of explanation, though perhaps he will not complete the sentence.
1.\p.m..\Here \
a.taken b.drawn c.given d.shown
2.Supposing one wants to make a telephone call at dawn, this would mean________.
a.the matter is important
b.the matter is somewhat important
c.the matter requires immediate attentiond. d.it is a matter of life and death
3.According to this passage , time plays an important role in _________. a.everyday life b.shool life c.communications d.private life
4. The best title for this passage is_________. a. the voices of time b.the importance of time
c.the importance of an ammouncement d.time and tide wait for no man
5.According to the passage, the author of the article may agree to which of the following statements?
a.It is appropriate to send your invitation cards three or four days before a dinner party date in U.S.A.
b.It may be appropriate to send your invitation to your guests three or four days before a dinner party date in some cultures.
c.It is best for one to make telephone calls at night because it costs much less.
d.If one is less than 5 minutes late, he has to make a short apology.
第22篇答案：cdcab
Liberia, the oldest independent Negro state in West A frica, has been struggling for survial ever since its foundation in 1822.Progress has been hampered by constant hostility between the American Negroes whose families returned there in the early 19th century, and the West Africans whose ancestors
never left the continent. Though the two groups are of the same race, they are divided by language and outlook and regard each other with deep suspicion creating a conflict which was not foreseen by Liberia's founders.
In addition, neighboring states, native tribel,disease, and poverty have made life dangerous and difficult. The government has tried desperately, through loans and a trickle of trade, to make ends meet.Anxiety about financial matters lessened somewhat when,in 1910, the United States accepted responsibility for Liberia's sruvival. However, not until Harvey Firestone, the American rubber king,decided that the United States must produce itsown rubber----with Liberia as the site of the rubber plantations----did liberia have much hope of paying its debts and balancing its budget.
The rubber industry,founded in the 1920's ,and the activity that followed it brought both progerss and profit to Liberia. Before that time Liberia had no roads, no mechanical transport and no good port; its people had little education and few tools. Liberians feel that the country is being ruled by rubber. For this reason, the recent discovery of iron ore is important. Liberian leaders are trying to moderate the power of the ruvver industry and to estaglish the country's political and economic independence.
1.Liberia has been in idffculty since its independence mainly because______. a.the american negroes do not want to help the country.
b.there have been constant hostillity and suspicion between different tribes in the country.
c.there haven been constant hostility and suspicion between two groups of the same tride.
d.the goverment has adoped a wrong policy
2.\government has tried desperately, through loans and a trickle of trade, to make ends meet.\ a.the goverment has to borrow money from others b. the goverment has to lend money to others c.the goverment doesn't have to borrow or lend money d.the goverment has either to borrow or to lend money
3.The country's finance began to improve a bit in________. a.1822 b.1910
c.1920 d.1920's
4.The Liberians's attitude on to improve a bit in_______. a.a total agreement b.a total disagreement c.a hostility
d.not a total agreement
5.The best title for this passage is_______. a. American Negroes in West Africa b.liberia----- a poor country c.liberia and its development
d.liberia ----a country with rich rubber and iron
第23篇答案：ccbdc
第24篇
The accuracy of cientific observations and calculations is always at the mercy of the scientist's timekeeping methods. For this reason,scientists are interested in devices that give promise of more precise timekeeping.
In their search for precision, scientists have turned to atomic clocks that depend on various vibrating atoms or molecules to supply their \is possible because each kind of atom or molecule has its own characteristic rate of vibration. The nitrogen atom in ammonia , for example, vibrates or \24 billion times a second.
One such atomic clock is so accurate that it will probaly lose no more than a second in 3000 years. It will be of great improtance in fields such as astronomical is a sesium atom that vibrates 9.2 billion times a second when heated to the temperature of boiling water.
An atomic clock that operates with an ammonia molecue may be used to check the accuracy of predictions based on Einstein's relativity theories, according to which a clock in motion and a clock at rest should keep time differently. Placed in an orbiting satellite moving at a speed of 18000 miles an hour, the clock could broadcast its time readings to a ground station, where they would be compared with the readings on a similar model. Whatever differences develop would be checked against the differences predicted.