七人表决器当选举人大于或等于4时为通过，绿灯亮；反之不通过时，黄灯亮。描述时，只须检查每一个输入的状态（通过为“1”，不通过为“0”），并将这些状态值相加，判断状态值和即可选择输出。-Seven voting machines when voters is greater than or equal to 4 through the green light　the other hand does not pass, the yellow light. Descr iption, just check the status of each input (through the " 1" , without " 0" ), and these states are added to determine the state values and to select the output.