A job requires 2 fitters and 2 electricians to complete. There are 2 fitters, 2 electricians, and 1 fitter and electrician. Choose 4 people from 5 people to complete this task. How many different ways of selection are there?
某工作需要钳工2人和电工2人共同完成．现有钳工2人，电工2人，另有1人钳工、电工都会．从5人中挑选4人完成这项工作，共有多少中不同的选法．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<result>5</result>