阅读短文，掌握其大意，选择可以填在横线上的最佳选项。
It was a fine spring day with beautiful flowers in the park. A young man arrived early and waited for his 1 under a big tree. But he was so short-tempered (性急的) that he wasn't in the mood to 2 the scenery.
Suddenly, an angel appeared, "Here is a button (按钮). If you don't want to 3, just turn the button to the right. You can skip over (跳过) any time period if you want to."
The man happily held the button and turned it softly. Oh! How amazing! His girlfriend appeared before him and was gently 4 him! "How I wish our wedding ceremony could be held now!" He turned the button once again. A great wedding 5 in front of him. The beautiful bride (新娘) was standing next to him and the band was playing 6 music. He lost himself in it deeply.
The 7 in his heart kept coming out: I also want a big house with a garden in the front. He turned the button. Then he wished for children. All of a sudden, a group of lovely children were playing 8 in the huge living room. Again, he jumped at the chance to tum the button to the right.
How time flew! Before he could see beautiful flowers in the garden, everything had been covered in deep snow. Looking at himself again, he found his hair totally 9. He had already become so old.
He felt so sad. He would rather enjoy life step by step than watch it go by in such a hurry. He quickly turned the button to the 10.
Once again, he was waiting for his lovely girlfriend under that big tree.
，神舟飞船在地球表面附近的圆形轨道运行周期为
，火星质量与地球质量之比为
，火星半径
与地球半径之比为
，则
的定义域是 （ 
）