中国古代四大名著之一的      被美国NBC电视台改编并取名为《The Monkey King》(猴王)。文中空格处应填写  (    )

若椭圆$C_1:\frac{x^2}{a_1^2}+\frac{y^2}{b_1^2}=1(a_1>b_1>0)$和椭圆$C_2:\frac{x^2}{a_2^2}+\frac{y^2}{b_2^2}=1(a_2>b_2>0)$的焦点相同且a₁>a₂.给出如下四个结论：
①椭圆C₁和椭圆C₂一定没有公共点；          ②$\frac{a_1}{a_2}>\frac{b_1}{b_2}$；
③$a_1^2-a_2^2=b_1^2-b_2^2$；                ④$a_1-a_2<b_1-b_2$.
其中，所有正确结论的序号是（   ）

    Which of your hands do you use most ? Very few of us use both of our hands well. Most of us are right-handed. Only about five people out of a hundred are left-handed. New-born babies can take things with either of their hands, but in about two years they like to use their right hands. Scientists don't know why this happens. They have studied it. They think our animal ancestors(祖先) are right-handed. This may not be true. Monkeys are our closest relations in the animal world. Scientists have found that monkeys like to use one of their hands more than the other—but it can be either hand. There are as many right-handed ones. Next time you visit the zoo, watch the monkeys carefully. You'll see that some of them will swing(摆动)from their right hands and others will use their left hands. But most human beings(人类) use their right hands better and this makes life difficult for the left-handed ones. We live in a right-handed world.