2. since.它引出的时间状语常与现在完成时连用。

1. has been.句中无动词，由“是”可知要用be；结合第2题可知要用be的现在完成时态。

4、根据上下文和括号里的汉语提示，在下面的空白处写出正确的单词和短语，使短文意思完整。

　　 Perhaps more than any other people， Americans have come to depend on their cars. The family car (1)______(一直是) a common thing (2)______ (从……以来) the early twentieth century， and it has changed American life. Many people have moved (3)______(外面) of the large cities to the suburbs. Some Americans spend (4)______(每天两小时) or more in their cars (5)______(去上班) and home again. Cars have become the (6)______(工具) of transportation for most Americans going shopping， and even going on vacations.

　　 Americans (7)______(过去常常) like big cars， and gasoline used to be very inexpensive. Recently， (8)______(然而)， the cost of gasoline has increased； smaller cars have become (9)______(更常见)。 Also foreign cars have become very common. Americans have bought (10)______(大量的) Japanese and German cars. They have bought cars from several other countries as well.

　　 「答案与解析」

　　 美国多数人都拥有汽车，因此有“车轮上的民族”之称，本文就是讲美国人使用汽车的一些情况的。

1. among.表示最高级的比较范围，意为“在……中”，一般用of或among，等介词，此处已有首字母a，所以是among.

3、根据短文内容在空格处填入一个适当的单词，使短文的意思完整，需填单词的第一个字母已经给出。

　　 It is well-known that man is much cleverer than any animal. But which is the cleverest a_______(1) the animals？ Some scientists t_______(2) it should be Alex， an African grey parrot. He is unlike any other animal. He can really t_______(3) with people！

　　 When he says “come here”， he really w_______(4) someone to come up to him.“

　　 “Alex is as clever as a c_______(5) of 2 or 3 years old，” says Dr. Pepperberg. “He does not just repeat the s_______(6) he has been taught. He u_______(7) the words！”

　　 Alex can tell about 50 d_______(8) things， name 7 colours and count from 1 to 6. Is the parrot actually thinking in the w_______ (9) how man does？ Nobody can say. But the q_______ (10) is very interesting.

　　 答案与解析」

　　 本文论述了非洲灰色鹦鹉被一些科学家认为是最聪明的动物。

10. question.上文“Is the parrot…？”提出的是一个问题。

9. way.根据句意“他的思维方式是否与的思维方式一样呢？”。搭配：in the way用这种方式。

8. different.根据things是复数及首字母的提示可知是指不同的(different) 事物。

7. understands.从后文的描述可知，他不但会重复教他的声音而且还明白其意思。

6. sounds.由前文的talk和后文的words可知是重复教他讲话的声音。