—Where is my desk?
—_____ is here. [ ]
A. This
B. It
C. That
D. My desk
答案：B
vertebral-basilar syndrome
圆O1是以R为半径的球O的小圆，若圆心O1到球心O的距离与球半径面积S1和球O的表面积S的比为S1：S=2：9，则圆心O1到球心O的距离与球半径的比OO1：R=______．
