I wonder why Mr Green looks worried today.

I'm not sure, but he ________ a small accident driving here.

[　　]

　　Drawing a picture is the simplest way of putting an idea down on paper. That is 1 man first began to write, six thousand years ago or 2 . The alphabet we now use came down to us 3 a long period of time. It was 4 from the picture-writing of ancient Egypt.

　　Picture-writing was useful in many 5 . It could be used to express ideas as well as 6 . For example, a drawing of a 7 meant the object “man”. 8 a drawing of a man 9 on the ground with a spear in him meant “ 10 ”.

　　Besides the Egytians, the Chinese 11 the American Indians also developed ways 12 writing in pictures. But only 13 much could be said 14 . Thousands of pictures would have been needed to express all the ideas that people 15 . It would have 16 many thousands more to express all the objects 17 to people. No one could 18 so many pictures in his lifetime. 19 could anyone learn the meanings of all 20 drawings in a lifetime.

1．

[　　]

2．

[　　]

3．

[　　]

4．

[　　]

5．

[　　]

6．

[　　]

7．

[　　]

8．

[　　]

9．

[　　]

10．

[　　]

11．

[　　]

12．

[　　]

13．

[　　]

14．

[　　]

15．

[　　]

16．

[　　]

17．

[　　]

18．

[　　]

19．

[　　]

20．

[　　]

 The accident      caused by a dog running across the road, but we don’t know for sure.  

    A．could have been                   B．must have been

    C．might have                        D．should have

 

As we all know, he has regretted wasting the precious time when he         studied hard playing computer games at school.

       A．should have     B．would have      C．might have       D．must have