What is the perimeter of a parallelogram whose adjacent sides are 4 cm and 6 cm respectively?
一组邻边分别是4厘米和6厘米的平行四边形，它的周长是多少．
<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>