地球瞬时自转轴在地球上随时间而变，称为（）。
参考答案：地极移动—极移
最常见的鹿角形结石是
A．肾结石B．肾结核C．肾肿瘤D．肾下垂E．肾水肿
---What attracts people to California is its pleasant climate and relaxed lifestyle.
---This is ____ each year a great number of people from all over the world try to ____ to California.
A．how; immigrate
B．Why; immigrate
C．because; remove
D．why; remove
