小博士：我们在这几个月的学习里，接触到不少的疑问词，其中疑问代词占大多数。那么疑问代词有哪些？又有哪些用法呢？看看下面的总结吧！

　　1)疑问代词在句中起名词词组的作用，用来构成疑问句。疑问代词有下列几个：

　　指人：who，whom，whose

　　指物：what

　　既可指人又可指物：which

　　2)疑问代词在句中应位于谓语动词之前，没有数的变化，除who之外也没有格的变化。无论是做疑问代词还是限定词，which和what所指的范围都是不同的。what所指的范围是无限的，而which则指在一定的范围内，例如：

　　Which movies do you like best?

　　你喜欢哪几个部电影？

　　What movies do you like best?

　　你喜欢什么样的电影？

你明白了吗？那么就请选用刚才我讨论过的疑问词完成下面句型转换。

1　　My favorite subject is science.

________ ________ your favorite subject?

2　　He likes art best.

________ ________ he like best?

3　　My science teacher is Mr Green.

________ ________ your science teacher?

4　　He's really busy today.

________ ________ really busy today?

5　　Betty's backpack is in her bedroom.

________ backpack is here?

小博士：细心的同学们肯定发现了有些名词有单数(singular)和复数(plural)两种形式，而有些名词只有单数形式，这是怎么回事呢？让我来告诉你吧。英语中，名词按其所表示的事物的性质，可分为可数名词(countable noun)和不可数名词(uncountable noun)，可数名词有复数形式，不可数名词一般没有复数形式。名词单数变复数的变化规则见下表。

比一比，看谁写的单词多！

1　　直接加-s的单词有：________________________________.

2　　加-es的单词有：___________________________________.

3　　变y为i再加-es的单词有：__________________________.

4　　不规则变化的单词有：_______________________________.

　　小博士：时间名词前可以用的介词在初中阶段学的主要有5个，可以用下面的速记歌来帮助学习。

　　年月之前要用“in”，遇到日期却用“on”。

　　上午下午又是“in”，某日上下午“on”帮忙。

　　正午、晚上用“at”，黎明、午夜也相宜。

　　时钟之前也是“它”，差分过秒不用“它”

　　说“差”要用介词“to”，说“过”要用“past”。

　　多说多练牢牢记，学好英语本事大。

记住了吗？那么就请信心十足地动手做下面的介词填空练习吗：

1　　My birthday is ________Dec. 1st.

2　　He was born ________ 1991.

3　　The People's Republic of China(中华人民共和国) was founded (成立) ________ October 1st 1949.

4　　It was happened(发生) ________ the morning of a cold day.

5　　－Do you have time ________ Sunday evening?

　　 －I'm afraid not. But I am free ________ the afternoon.

6　　I usually go to bed ________ 9:00, but ________ weekends, I'm later.

7　　New school year begins ________ September.

8　　You can get cheap things ________ this time of year.

9　　We enjoy ourselves ________ Children's Day.

完形填空

　A pine tree in California was regarded （看作）the oldest tree in the world. People thought 　1　 was nearly 5,000 years old. 　2　　 　they could not be 　3　　 　. Then someone 　4　 the tree down 　5　　 　a chain saw （链式锯）。Kiling the 　6　　 　tree in the world was a 　7　　 　thing to do. But when the tree 　8　　 　down, 　9　　 　knew its 　10　　 　. It was 4,900 　11　　 　.

　How can you 　12　　 　the age of a tree? If you ever 　13　　 　a tree that has just 　14　　 　cut down, take a look at the cut 　15　　 　. You will see rings. There are little rings in the middle. 　16　　 　each ring is a larger one. The ring 　17　　 　the bark （树皮）is the biggest one of 　18　　 　.

　Count these rings. A tree grows one ring each 　19　　 　. A ten-year-old tree has ten rings. A sixty-year-old tree has sixty rings. 　20　　 　rings does a 4,900-year-old tree have?