There are three number cards, which are 1, 2 and 3, and 2 are randomly drawn from the three. What is the probability that the difference between them is 2?
有三张数字卡片，分别是1、2和3，从三张中任意抽出2张，它们的差是2的可能性是多少
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>