阅读下面短文，请从方框中选出适当的句子填入文中的适当位置，使短文内容完整正确。

This is a street crossing.  1  Drivers must watch the lights carefully.
  2  When there is a red light, the cars going straight must stop. They must wait until the red light
changes to green.  3  Sometimes the cars want to make a right turn or a left turn. They can make a right
turn when the light is green or red.  But they must wait until the green light is shining if they want to turn left.
  4  They can't see the difference between red and green. These people must not drive, or else there will be accidents.  5  

We must keep our streets safe. There are red and gree,n lights at each corner. Then they can go on. When there is a green light, the cars may go on. Some people are color-blind(色盲).

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