Different things usually stand for different feelings. Red， for example， is the color of fire， heat， blood and life. People say red is an exciting and active color. They associate(使发生联系) red with a strong feeling like 1 。 Red is used for signs of 2 ， such as STOP signs and fire engines. Orange is the bright， warm color of 3 in autumn. People say orange is a 4 color. They associate orange with happiness. Yellow is the color of __5__. People say it is a cheerful color. They associate yellow too， with happiness. Green is the cool color of grass in __6__. People say it is a refreshing color. In general， people __7__ two groups of colors：
