【科技讯】2015年5月24日消息，太空探测器“旅行者1号”已经飞出太阳系，成为首个进入星际空间的人造物体，为寻找地外文明又迈进了一步。材料中比“太阳系”高一级的天体系统在天体系统层次图中的位置正确的是（    ）

—Hi, Mrs. Green How was your trip to the United States?

—It was wonderful____

—____

—I was there for a month.

—Great.____

—Yes, it's a wonderful and exciting city.

—____

—The city is the main business and cultural center in the Midwest It's famous for its music opera and theaters as well as for its excellent museums.

—____

—Yes, sure. What would you like to know?

海南省三亚市异地养老老年人协会近日表示，今年东北三省将有20万老人奔赴三亚过冬，北方老人到海南过冬的主要原因是（　　）