Question

  Even during the ancient days,traffic in big cities was often heavy. Police officers had to stand at busy crossings the whole day. They often got 21 after they worked all day long. So they 22 a small lantern (提灯) with red and green lights. Red meant “ 23 ” and green meant “be careful” .The lantern was 24 by a lever (控制杆) below so that the right light faced traffic. 25 ，this lantern was often crispy because of much gas in the light bulb.

   As cars were 26 ,the situation got even worse. An American policeman,William Potts,decided to do 27 to solve the problem.

   One day,while he was walking along a railway,Potts 28 the railroad signals. Then he got an idea—why not use them on 29 ? So Potts used red,yellow,and green railroad lights to make the 30 fourway traffic lights in the world. It was used in 1920 on a corner in his city. In the year,fifteen of the new lights were used across his state.

21. A. tired   B. happy      C. busy      D. sleepy

22. A. bought   B. produced   C. carried   D. created

23. A. remain   B. stop       C. rise      D. go

24. A. knocked   B. divided   C. threw      D. operated

25. A. However   B. Besides   C. Instead   D. Even

26. A. found     B. invented C. discovered      D. seen 

27 .A. everything   B. anything

   C. something   D. nothing

28. A. broke       B. obeyed       C. guided   D. noticed

29. A. buildings   B. streets   C. cars     D. courts

30. A. first      B. other        C. next     D. last 

Answer 1