二、疑难详解

1. In the 18th century, Benjamin Franklin cinducted a number of experiments in which he showed what electricity is.在18世纪，本杰明富兰克林进行了许多次关于电的实验。

[问]...in which he showed what electrivity is. in + which 引导定语从句，修饰先行词experiments。 这里which不能由that替换。

(2)...what electricity is 宾语从句，做show的宾语。

(3)A number of...“许多，大量”，接可数名词复数，谓语要用复数形式;the number of...“……的数量”谓语动词应该用单数。

例如：A number of peasants are working inthe fields with the sun burning in the shy. 许多农民顶着烈日在地里耕作。

2. Having realized that I could use a kite to aftract lightning. I decided to do an experiment. 当我意思到能用风筝来接收闪电后，我决定做个实验。

[问]Having realized that ... 在句子充当什么成分?

[答]Having realized that ... 现在分词短语做时间状语。(=when I had realized that I could use a kite to attract lightning, ...)

3. Most kites are made of paper, but a kite made of silk will last longer in weather with rain and strong winds. 大多数风筝是由纸做的，但用丝绸制的风筝在雨和大风的天气中持续的时间会长一些。

[问]made of silk 在句中作何成分?be made of 与be made from 有何区别?

[答] made of silk 过去粉刺短语所定语，修饰a kite, he made of...由……构成(看得出原材料);be made from 由……构成(看不出原材料)。

4. The pieces should be just long enough to reach the comers of the handkerchief.那木头片的长度应该达到手帕的四个角。

[问]enough在句中如何用?reach是什么意思?

[答](1)enough to ..." 足够……的”， enough修饰形容词时应放在形容词之后。例如：kind enough 足够善良的;careful enough足够仔细的。

(2)reach v. & n. 达到;够得着。例如：out of reach够不着。

5. Add a tail to the frame and tie a long string to the cross so you can control the kite.在架子上加一个把柄，在十字架上栓一根长细绳以便你能够控制那风筝。

[问]add...to...是什么意思?

[答]add...to...把……加到……。

例如：Please add an article to the sentence, then it is correct now .请在这个句子中加上一个定冠词，然后它就对了。

6. THis ribbon, which must not get wet, will protect you from the electricity.这根丝带一定不能变湿，它是用来保护你不被触电的。

[问]which must not get wet 作何成分， protect...from...是什么意思?

[答](1)...which must not get wet ，非限制性定语从句做定语，修饰This ribbon.

(2)protect ... from... “保护……免受……”，相当于prevent ... from ...;stop ...from...;keep ...from。

例如：We should prevent our environment from being polluted. 我们应该保护我们的环境免受污染。

7. Around the world, animals are used to test produce such as shampoo, skin creams and new cancer drugs. 在全世界，动物们被用来测试如洗发水，皮肤霜以及新的治癌药等产品。

[问]be used to do ..., be used to doing ... 和used to do 有何区别?

[答]be used to do ... 被用来做什么......

be used to doing ... 习惯于做……

used to do ...过去常常做……

8. They also believe that it is possible to use much fewer animals.

他们还相信用更少的动物测试是可能的。

[问]it is possible to do ...做……是可能的;

It is + adj. +to do ... it 是形式主语，真正的主语是动词不定式短语to do...

例如：It is difficult to learn two foreigh languages. 学会两门外语是困难的。

It is impossible to walk on the moon. 在月球上行走是不可能的。