two in one sets

Because their two sets of wings effectively flap as one, that in theory gives them little control over the aerodynamic forces on their body.

因为它们的两副翅膀叠在一起，在空气动力学的理论中，这意味着它们对自己身体缺乏控制力。

In one experiment, rhesus monkeys and university students had to choose the bigger of two sets of geometrical objects that appeared briefly on a computer monitor.

在一个试验里，电脑屏幕上快速地闪过两组几何体，恒河猴和大学生被要求在两组几何形状中挑选出比较大的那些。

So there are two things in which you distinguish arguments but the first one is sets of sentences.

有两种东西你们要与论点区分开,但是第一种是几组句子。