阅读理解

　　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 "ticking". This 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"ticks" 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.

　　1. Scientists expect that the atomic clocks will be ________.

　　a. more precise

　　b. absolutely accurate

　　c. more durable

　　d. indestructible

　　2. The heart of the atomichron is ________.

　　a. acesium atom

　　b. an ammonia molecule

　　c. a nitrogen atom

　　d. a hydrogen

　　3. From theselection, we may assume that temperature changes ________.

　　a. affect only ammonia molecules

　　b. may affect the vibration rate of atoms

　　c. affect the speed at which atoms travel

　　d. do not affect atoms in any way

　　4. Identical atomic clocks may be used to check ________.

　　a. the effect of outer space on an atomic clock

　　b. the actual speed of an orbiting satelite

　　c. the accuacy of predictions based on theories of relativity

　　d. all of Einstein's theories

　　5. Implied but not stated: ________.

　　a. Precise timekeeping is essential in science

　　b. Scientists expect to disprove Einstein's relativity theories

　　c. Atomic clocks will be important in space flight

　　d. The rate of vibration of an atom never varies

　　答案: aabcc

　　翻译

　　中国桥梁

　　中国的桥梁建设有着悠久的历史。中国古代桥梁以木材和石头为主要建筑材料,形式多样，极富特色。中国现存最古老的桥梁为隋代建造的安济桥，位于河北省赵县。安济桥又名赵州桥，桥长50.82米，桥宽9米，为国家重点保护的文物(cultural relic)。清朝末年，兰州黄河铁桥建成，标志着中国桥梁建设进入了以钢铁和混凝土(concrete)为主要材料的时期。如今，中国的桥梁建设保持着多项世界记录，中国跻身于世界桥梁建设强国行列。

　　China boasts a long history in bridge construction.With wood and stone as the major buildingmaterials, Chinese ancient bridges vary in forms andare highly distinct.Constructed in the Sui Dynasty, Anji Bridge, which is located in Zhao County, HebeiProvince, is the oldest existing bridge in China.Anji Bridge, also named Zhaozhou Bridge, is akey national protected cultural relic measuring a length of 50.82 meters and a width of 9meters.In the late years of the Qing Dynasty, Huanghe Iron Bridge in Lanzhou was completed,symbolizing that China's bridge construction stepped into an era of adopting steel andconcrete as the main materials for bridges.Now, bearing many world records, China standsamong world giants in bridge construction.

　　1.第二句中的“以……为主要建筑材料”可处理为状语，用介词短语with……as the major building materials表达，而“中国古代桥梁”宜译为“形式多样，极富特色”的主语，谓语部分“形式多样，极富特色”可处理为并列内容，用and连接，表达为vary in forms and are highly distinct.

　　2.第三句“中国现存最古老的桥梁…位于河北省赵县”的定语较多，可以拆译成两句。首先译出主要结构Anji Bridge is the bridge，“现存最古老的”有两个形容词，英语中的比较级或最高级形容词通常在其他形容词之前，故译为oldest existing.“隋代建造的”可处理为过去分词短语constructed in the Sui Dynasty 或which引导的定语从句。

　　3.第四句的主干是“安济桥为国家重点保护的文物”，故把“又名赵州桥”处理为插入语also named…;将“桥长50.82米，桥宽9米”处理为伴随状态的状语，用分词短语measuring a length of…and a width of…译出。

　　4.倒数第二句中的“兰州黄河铁桥”与“建成”之间是被动关系，翻泽时需把“建成”译为被动式wascompleted.“标志着中国…”是结果，故可处理为状语，用现在分词短语symbolizing that…表达。定语“以钢铁和混凝土为主要材料的”较长，可处理为后置定语，用现在分词短语adopting…as the main materials 表达，也可用介词短语with…as the main materials翻译。

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