Unit 1 What a Wonderful Time! Unit 2 Family and Friends Unit 3 At the Market Unit 4 What's in Fashion? Unit 5 Danger and Safety Unit 6 Watch for Fun! Unit 7 Nice Weather, Nice Mood Unit 8 Create an Image Unit 9 Stay in Touch Unit 10 Success Starts Early! 附：国际音标及发音练习 Keys to the Exercises
摘要
(1) Before roads needed traffic lights, railways had used signals (信号) to control train traffic.In early days,these signals included a ball andsomething that looked like a kite.When the kite was on top,it meant danger; when the ball was raised,it was safe. In 1841, a developed railway signal was used at the London station.It included a signal arm in the horizontal(水平的) position which meant "stop".The signal was painted red so that it was easy to see and could attract the drivers' attention. At night,oil lights were added on the top.A red light meant '6stop" and a white light meant the drivers could go on. In January 1876,a train knocked on another train running ahead on the same roads,because the signals were not clear enough.13 people were killed in the accident and the others were badly hurt. Then people changed the signal.The signal for '6stop" became a red light and a yellow light was added to tell the drivers to drive carefully.ln 1893,a green light took the place of the white light,because the white light was often mistaken for a street or house light. Since railway signals were introduced, city officials (官员 )decided to try them out on the roads of London. Choose the correct answer according to the passage. ( )1.In early days,what did people use to control train traffic? A.A ball. B.Something that looked like a kite. C.Lights. D.A and B. ( )2.What did a white light mean in 1842? A.The drivers must stop. B.The drivers could go on. C.It could attract the drivers' attention. D.It was dangerous.
