一个精原细胞有两对同源染色体A和a，B和b，经减数分裂后（没有交叉互换），形成的精子种类和数目分别是                    

①没有绝对值最小的有理数；        ②单项式- $\frac{2\pi x^2}{3}$ 的系数是 $-\frac{2}{3}$ ；

③所有有理数都有相反数和倒数；    ④如果|a|=a，那么a一定是非负数；

⑤－2017是单项式.

下列有关热的说法正确的是（）

写出下列词语的反义词： small-____

    Hi, I'm Tom. I'm a student. I'm eleven. My birthday is on 12th July. I go to school by bike. My father is a fireman. He uses water to put out fires. He's brave. He goes to work by bus. My mother is a doctor. She works in a hospital. She helps people. She goes to work by car. I like helping people, too. I want to be a doctor in the future. But my brother wants to fly a plane. He wants to be a pilot in the future.