英语四级考前每日一练(3)

　　Directions : There are 20 blanks in the following passage. For each blank there are four choices marked　A, B, C and　D on the right side of the paper. You should choose the ONE that best fits into the passage. Then mark the corresponding letter on Answer Sheet 2 with a single line through the centre.
　　In recent years a new farming revolution has begun, one that involves the 67 of life at a fundamental level -- the gene. The study of genetics has 68 rise to a new industry called biotechnology. As the name suggests, it 69 biology and modern technology through such techniques as genetic engineering. Some of the new biotech companies specialize in agriculture and are working feverishly to 70 seeds that give a high yield, that 71 diseases, drought and frost, and that reduce the need for 72 chemicals. If such goals could be achieved, it would be most 73 . But some have raised concerns about genetically engineered crops.
　　In nature, genetic diversity is created within certain 74．A rose can be crossed with a different kind of rose，but a rose will never cross with a potato．Genetic engineerin9，on the other hand，usually 75 taking genes from one species and inserting them into another in a(n) 76 to transfer a desired characteristic．This could mean，for example，selecting a gene which leads to the production of a chemical with antifreeze 77 from an arctic fish，and inserting it into a potato or strawberry to make it frost—resistant．In 78 ，then，biotechnology allows humans t0 79 the genetic walls that separate species．
　　Like the green revolution，80 some call the gene revolution contributes to the problem of genetic uniformity—some say even more so 81 geneticists Can employ techniques such as cloning and 82 culture，processes that produce perfectly 83 copies．Concerns about the erosion of biodiversity，therefore，remain：Genetically altered plants，however，raise new 84， such as the effects that they may have on us and the environment．“We are flying blindly into a new 85 of agricultural biotechnology with high hopes，few constraints，and little idea of the potential 86。”said science writer Jeremy Rifkin．
　　67. A．manufacture
　　B management
　　C．manipulation
　　D．maturity
　　68. A．got
　　B． lived
　　C．come
　　D．given
　　69. A．blends
　　B ．breeds
　　C ．broods
　　D blasts
　　70. A．hatch
　　B．patent
　　C．duplicate
　　D ．train
　　71. A．restrict
　　B．retrieve
　　C．reverse
　　D．resist
　　72. A．hazardous
　　B ．hydraulic
　　C ．hostile
　　D．harmless
　　73. A．surprising
　　B．disappointing
　　C．beneficial
　　D ．extreme
　　74. A．lines
　　B ．ages
　　C．space
　　D．limits
　　75．A．includes
　　B．involves
　　C．contains
　　D．comprises
　　76．A．attempt
　　B．case
　　C．point
　　D．regard
　　77．A．quality
　　B．quantity
　　C．priority
　　D．property
　　78．A．advance
　　B．part
　　C．essence
　　D．return
　　79．A．breach
　　B．blaze
　　C．brake
　　D．brand
　　80．A．where
　　B．as
　　C．what
　　D．so
　　81．A．that
　　B．when
　　C．if
　　D．because
　　82．A．skin
　　B．muscle
　　C．organ
　　D．tissue
　　83．A．resembling
　　B．identical
　　C．similar
　　D．alike
　　84．A．difficulties
　　B．height
　　C．issues
　　D．goals
　　85．A．spot
　　B．scheme
　　C．deadline
　　D．era
　　86．A．outcomes
　　B．mystery
　　C．navigation
　　D．destination
　　【结构剖析】论说文。本文主要介绍了基因工程在农业上的应用。首先指出由于基因工程的介入，农业发生了革命；接着I具体介绍了生物工艺化的意义以及基因工程的特征；最后讨论了生物工艺化引发的新问题。