A:to make fun of; at
B:to make fun of; i
C:to be made fun of; i
D:to be made fun of; with
用四只完全相同的滑轮和两根相同的绳子组成如图所示的甲、乙两个滑轮组,不计绳重和摩擦,则下列说法正确的是