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2．在何种情况下有可能预测某一给定的核苷酸链中“G”的百分含量？

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6．一段长度100bp的DNA，具有4¹⁰⁰。种可能的序列组合形式。

Robots The most sophisticated(先进的) Japanese robots, which have vision systems and work at very high speeds, are still based on American designs. Studies of robots, particularly computer control software, are considered to be generally less advanced in Japan than in America or Europe. Although industrial robots were originally developed as devices for simply handling objects, today their commonest uses are for more skilled work like welding(焊接), spray-painting and assembling components. In Britain, robot sales appropriately peaked in 1984, but have been declining ever since. This is partly because British wage rates are too low to make robots financially attractive and partly because engineers now have more experience with robots and are more aware of the difficulties of introducing them effectively. It has been calculated that a robot uses on average about 100 times more energy than a human to do an equivalent job. It is estimated that 20% of all comic book heroes in Japan are robots. This is an enormous number because comics are so popular that they make up a third of all material published in Japan. The reliability of robots is measured in their M.T.B.F. of mean time between failures. This has risen from about 250 hours in the mid-1970s to about 10.000 hours today (equivalent to working 18 hours a day for two years). One way robot manufacturers have increased reliability is to test every single component they buy, instead of the normal procedure of just testing a small sample. The biggest single benefit of introducing robots claimed by Japanese companies is that they increase quality control. Once programmed, the robots can work more accurately and consistently than humans, who can get tired and bored.Paragraph 2____________
A Ongoing ResearchB Extension of UseC Robot HeroesD Greater ReliabilityE Falling DemandF Hidden Danger

下图为用以展现进度的香蕉曲线图，图中曲线A为最早时间计划，曲线B为最迟时间计划，曲线C、D、E、F为实际进度，（50）表示延期。
（50）

A. C
B. D
C. E
D. F

4．在核酸双螺旋(如DNA)中形成发夹环结构的频率比单链分子低。发夹结构的产生需要回文序列使双链形成对称的发夹，呈十字结构。