设圆 C 与圆 (x-5) 2+y2=2 ，关于 y=2x 时称，则圆 C 方程为 ( )

Thedestructionofthetwintowers_________shockandangerthroughouttheworld．

设数列 {an} 的前 n 项和为 Sn，则 {an} 等差。

(1) S n4=n 2+2n, n=1,2,3

(2) S n4=n 2+ 2n +1,n=1,2,3

The opportunity to explore and play and the encouragement to do so Can ________the performance of many children ．

About 20 of the passengers who were injured in a plane crash are said to be in_____condition ．