7.该句的主干结构为“A method may replace the LD50.”“using a fixed amount ”和“which gives the same eventual information but uses fewer animals and does not require that they die”分别是分词短语和定语从句做method的定语。

　　本句译文：“另一种方法是使用固定量的有毒物质，能够给出同样的更终信息，但使用较少的动物并且不需要它们死亡，这个方法可以代替LD50.”

　　8.此句中that 引导的定语从句修饰techniques；因为从句过长，所以放到了主句谓语are now available 之后。这是由于修辞需要而引起的倒装。

　　本句译文：“现在已有很多别的新技术，使更多的研究能在试管里进行，以便发现化学药品是否产生有毒的生物效果。”

　　The number of animals used in laboratory tests has declined over the last 20 years. This is partly due to alternatives and partly to the fact that experiments are better designed so fewer need to be used ——healthier animals provide better experimental results. ⑨For example， it used to take 36 monkeys to test a sample of polio vaccine， now it takes only 22. Also， lack of money has reduced the number of animals used - they are expensive to buy and expensive to keep.

　　9.句中“that”引导同位语从句修饰the fact； fewer 之后省略了experiments .其中due to 表示“由于…”的意思。

　　本句译文：“这部分地是由于采用了替代的方法，部分地是由于实验比以前设计得更好，所以需要的动物就少了。”

　　Birmingham University now has Britain‘s first department of Biomedical Ethics. Professor David Morton of the department is involved in animal research and is concerned with reducing animal suffering as much as possible. Animals spend 95% of their time in their cages and refinement also means making their lives better when not undergoing tests. This includes keeping them in more suitable cages， allowing social animals like dogs to live together and trying to reduce the boredom that these animals can experience.

　　In Professor Morton‘s laboratory， rabbits live together in large runs， filled with deep litter and boxes that they can hide in. The researchers have also refined some experiments. In the US， one experiment in nerve regeneration involves cutting a big nerve in a rat’s leg， leaving its leg paralysed. ⑩In Morton‘s lab， the researcher cuts a small nerve in the foot. He can see if it can regrow and the rat can still run around its cage.

　　10.句中 leaving its leg paralysed 是现在分词短语作 cutting 的结果状语，其中paralysed是宾语补语。

　　本句译文：“在美国，进行一次神经再生实验要在老鼠腿上切掉一大段神经，结果就把它的腿弄瘫痪了。

　　Even with these new developments in research， only a tiny proportion of all tests are done without using animals at some stage. The use of animals in experiments cannot stop immediately if medical research is to continue and consumer products are to be properly tested， and Professor Blakemore believes that sometimes there are no alternatives：

　　Wherever possible， for both ethical and scientific reasons， we do not use animals. ⑾But cells live in animals and we can only really see how they behave when they are inside animals. We cannot possibly reproduce in a test tube or a computer model all the complex reactions of the body to a drug or a disease.⑿ When it comes to research into heart disease and its effects on the body， or diseases of the brain for example， we do not have adequate substitutes for the use of animals.⒀

　　11.句中Wherever possible，的完整表达为Wherever it is possible，意为“不管在哪里，只要有可能”。

　　例如：Whenever possible， he would practice speaking English.

　　不管什么时候，只要有可能他就练习说英语。

　　本句译文：“只要可能，为了道德的和科学的两种理由，我们不使用动物。”

　　12.句中all the complex reactions of the body to a drug or a disease是reproduce的宾语，因为过长所以放到状语in a test tube or a computer model.后面。

　　本句译文：“我们不可能在试管里或用计算机模型模拟出身体对药物或疾病的全部复杂反应。”

　　13.句中heart disease and its effect on the body 和disease of the brain 做research into 的并列宾语。“for example”是针对由when 引导的整个状语从句而言，因此译成汉语时应放到句首。

　　本句译文：“例如当研究心脏病和它对身体的影响时，或者当研究大脑疾病时，我们没有充分的代用品来代替动物。”

　　As research techniques become more advanced， the number of animals used in experiments may decrease， but stopping testing on animals altogether is a long way away. ⒁

　　14.这是一个由but并列的两个分句。前一句中，as引导的从句作伴随时间状语，后半句中stopping testing on animals altogether 是动名词短语作主语，注意stop后面的非谓语动词的用法。（stop doing sth / stop to do sth）

　　本句译文：“随着研究技术的日益先进，用于实验的动物的数量可能会减少，但距离彻底停止使用动物还很遥远。”

　　Text B Let‘s Stop Keeping Pets

　　New Words

　　1.pet n. 宠物，爱畜

　　a. 宠爱的，表示亲昵的

　　2.delightful a. 令人高兴的；讨人喜欢的

　　3.humanity n. 1.人性，博爱，仁慈；2.人类

　　4.negative a.1.否定的，否认的；2.反面的，消极的；3.[数]负的，[电]阴性的

　　n. 1.负片，底片；2.负数