A、food
B、commodity
C、beautiful islands and beaches
D、technology
A、food
B、commodity
C、beautiful islands and beaches
D、technology
A、boring
B、demanding
C、nagging
D、impractical
High technology _76_ the most startling advances in helping the elderly . In _77_ to the well-known artificial heart implantation, there are efforts underway to _78_ artificial lungs , livers , and bones . An electric ear is _ 79_ seventy-five percent effective . The implants will _80_ better medical care by _81_ minute does of drugs into the body continuously .
For the older people ,even the simplest tasks can be difficult , _82_ impossible to perform. . American business have responded _83_ their needs with a _84_ of inexpensive but useful _85_ Companies have designed extra-efficient can openers that _86_ people whose hands have become _87_ weak to open cans easily . There are devices that allow people to pull on a pair of socks _88_straining their backs . Combs with long handles and U-shaped back brushes are _89_ for those who can not reach as _90_ as they could when they were young .
71. A) Seeing B) Meeting C) Facing D) Matching
72. A) chance B) challenge C) call D) change
73. A) valuable B) comprehensive C) considerate D) considerable
74. A) how B) why C) who D) whom
75. A) with B) to C) upon D) for
76. A) protects B) profits C) proclaims D) promises
77. A) relation B) contrast C) addition D) proportion
78. A) discover B) promote C) assemble D) develop
79. A) thus B) still C) already D) yet
80. A) permit B) persist C) serve D) pursue
81. A) removing B)releasing C) relieving D) replacing
82. A) always B) usually C) eventually D) sometimes
83. A) to B) at C) with D) on
84. A) set B) variety C) series D) group
85. A)production B)produce C) products D) sales
86. A)enable B) make C) cause D) encourage
87. A) so B) very C) too D) rather
88. A) by B)without C) in D) through
89. A) valuable B) ready C) near D) available
90. A) long B) good C) far D) much
阅读理解。 |
The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is hard to imagine what life would be like without them. When there is a power failure, people grope about in flickering candlelight, cars hesitate in the streets because there are no traffic lights to guide them, and food spoils in silent refrigerators. Yet, people began to understand how electricity works only a little more than two centuries ago. Nature has apparently been experimenting in this field for million of years. Scientists are discovering more and more that the living world may hold many interesting secrets of electricity that could benefit humanity. All living cells send out tiny pulses of electricity. As the heart beats, it sends out pulses of record; they form an electrocardiogram, which a doctor can study to determine how well the heart is working. The brain, too, sends our brain waves of electricity, which can be recorded in an electroencephalogram. The electric currents generated by most living cells are extremely small,often so small that sensitive instruments are needed to record them. But in some animals, certain muscle cells have become so specialized as electrical generators that they do not work as muscle cells at all. When large numbers of these cells are linked together, the effects can be astonishing. The electric eel is an amazing storage battery. It can send a jolt of as much as eight hundred volts of electricity through the water in which it lives. (An electric house current is only one hundred and twenty volts, but two hundred and twenty volts in China.) As many as four-fifths of all the cells in the electric eel's body are specialized for generating electricity, and the strength of the shock it can deliver corresponds roughly to length of its body. |
1. Electricity was invented ______. |
[ ] |
A. when man had no candles B. about 200 years ago C. to be operating computers D. by Thomse Edison |
2. The following things can send out pulses of electricity except ______. |
[ ] |
A. electric eels and human hearts B. Electrical generators and animal muscle C. Stones and dry wood D. human brain and living cells |
3. The electric current send out by an eel can be ______. |
[ ] |
A. as much as 800 volts B. about one hundred and twenty volts C. as high as the house current in China D. stored in the water where it lives |
4. From this shot passage we can infer ______. |
[ ] |
A. the shorter an eel is, the stronger electricity it produces B. we can always feel the electricity produced by living cells C. human beings get their knowledge about electricity from nature D. people learn about electricity from eels |
A、E=0, V>0.
B、E=0, V<0.<br> C、, V>0.
D、, V<0<br>
A、in
B、on
C、for
D、by
A、the marginal product of labor in the production of cloth times the price of cloth.
B、the ratio of the marginal product of labor in the production of cloth to the marginal product of labor in the production of food times the ratio of the price of cloth to the price of food.
C、the slope of the production possibility frontier.
D、the average product of labor in the production of cloth times the price of cloth.
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