8. We have been trying to pin down by experiments what people mean by these expressions in specific contexts，…
pin作名词用时指“别针，大头针”，如a safety pin （安全别针）；作动词用时指“别住”；“使不能行动”，pin down的意思是“准确说明”，“牵制”。如：

1） He pinned a badge on his jacket. （他在外套上别了一枚徽章。）

2） She pinned the papers together before giving them to the manager. （把文件给经理前，她用针把它们别好。）

3） They pinned him down to a promise. （他们迫使他履行诺言。）

4） We are trying to pin down his speech. （我们正努力准确说明他的讲话。）

两个by在句中都是介词，表示“靠，用，通过”，如：

1） What do you mean by that？ （你这样讲是什么意思？）

2） He put the young man in an awkward situation by asking him some personal questions.

（他通过问一些私人性问题使那个年轻人陷入尴尬。）

9. …we find that the number depends of course on the items involved.

…the size of the population of items influences the value assigned to an expression.

上面两句中的过去分词involved和assigned其前都省去了that （which） are （is），做定语修饰items和value.

本课主要短语

1. be made up of

2. in part

3. be likely to

4. be left with

5. allow sb. to do sth.

6. out of the question

7. not so much…as…

8. be reduced to

9. pin down

10. compare with

11. be certain to

12. in place of

Text B    it never rains but it pours！

谚语

1. There is no smoke without fire.

2. Don't wash your dirty linen in the public.

3. It's no use crying over spilt milk.

4. Make the best out of a bad job.

5. It never rains but it pours.

6. Every dog is allowed one bite.

7. One man's meat is another man’s poison.

8. Let sleeping dogs lie.

9. He who rides a tiger is afraid to dismount.

10. A friend in need is a friend indeed.

11. There is no such thing as a free lunch.

短语表达

1.  relevance to / be relevant to

What he said had no relevance to the present question.

They could not forward any relevant proof.

2.  believe in

I believe him but I don't believe in him.

He believes in Christianity.

3.  pass on to

Would you please pass this message on to Xiao Li？

Thank you for passing the news on to me.

4.  in the form of

He showed his appreciation to her in the form of a letter of hanks.

They gave the children a lot of help in the form of books.

5.  a reminder of

This proverb can be used as a reminder of the correct way to behave.

This picture is a reminder of my past.

6.  in times of

They are said to be more intelligent in times of difficulties.

This could be a comfort in times of trouble.

7.  be native to

Rice is believed to be native to China.

This saying is native to the American Indians.

8.  go wrong

When anything goes wrong with his car he will hasten to his auto repairman.

I don't know what has gone wrong with my computer.

9.  be b