[单项选择]About 150 years ago the children of a poor farmer who lived in South Africa found a pretty pebble on the bank of a river.（）
A. 一百五十年前，南非孩子在一条河边的银行找到一块美丽的鹅卵石。
B. 一百五十年前，一个贫穷农夫的孩子们发现一块漂亮的鹅卵石在河岸上。
C. 大约一百五十年前，南非一个贫穷农夫的孩子们在河岸边发现了一块美丽的鹅卵石。
D. 大约在一百五十年前，南非有一个贫穷的农夫，他家的孩子在河岸边拾到一块漂亮的鹅卵石。
E. 大约在一百五十年前，贫穷农夫的孩子们在南非在河岸上找到了一块美丽的鹅卵石。

[单项选择]

About 150 years ago the children of a poor farmer who lived in South Africa found a pretty pebble (鹅卵石) on the bank of a river. The pebble shone brightly in spots. The children took the pebble home and showed it to their mother. Then they tossed (扔) it aside. The next day a neighbour saw it and offered to buy it. The children and the mother told him that he could have it for nothing. Who ever heard of selling a pebble
The pebble turned out to be a large diamond. No one had known that there are diamonds in South Africa. Today a large part of all the diamonds in the world come from a region not far from the place where the children found their bright pebble.
Diamonds are crystals of carbon. Carbon is a very common material. Coal, for example, is made up mostly of carbon. But the carbon of coal is not in crystal form. Clear crystals of carbon are very rare.
The word "diamond" comes from a Greek word meaning "the unconquerable". The diamond
A. they were good neighbours
B. they didn’t need money
C. they thought it silly to sell a pebble
D. they didn’t know it was a diamond

[单项选择]About four years ago, Kerry Sturgill found herself at a career crossroads: Should she stay in an industry populated by extroverts(外向型的人) or jump ship to a more reflective place where introverts like her were in the majority
Career counselors had told her to get out of the highly extroverted public relations fields " so you can be happy and do what you are. " Among the less fast-paced areas they pointed to: art, scientific research, data analysis.
Such a move is definitely the right road for many introverts struggling to fit into an extroverted workplace.
So, just what is an introvert anyway It’s someone who is energized by thought and reflection, while extroverts are energized by socializing. Introverts naturally need to think before they speak. Extroverts use the speaking process to figure out what it is they want to say.
And, needless to say, there are pluses and minuses to both personality types.
Still, in the modern world where as many as two-thirds of the
A. introverts should try to avoid working in a highly extroverted environment
B. introverts should try to change themselves to fit into an extroverted working environment
C. extroverts should work in less fast-paced areas such as art and scientific research
D. introverts can be happier if they can find jobs in the field of public relations

[单项选择]

About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along fine on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course: The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.
The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoo
A. quite natural
B. sugar, minerals and vitamins
C. some rare vitamins
D. organic nitrogen compounds