5. “Would you please place the piano with its back a________ the wall? In case you might damage it.”

4. There are strong a___________ for and against capital punishment.

3. I made an a_____________ to my host and left early.

2. He caused his parents great a__________ by cycling long distance alone.

1. The a_____________ of the royal birth was broadcast to the nation.

17．给定两个长度为1的平面向量和，它们的夹角为。如图所示，点C在以O为圆心的圆弧上变动.若其中,则的最大值是=________.

瑞安中学2008学年第二学期高二年级期末考试

16．由“若直角三角形两直角边长分别为a、b，则其外接圆半径r =” 类比可得“若三棱锥三条侧棱两两垂直， 侧棱长分别为a、b、c，则其外接球半径r =　　　　

15．设是偶函数，若曲线在点处的切线的斜率为1，则该曲线在点处的切线的斜率为　　　　　　　　　 ．

14．在平行六面体中，若两两所成的角都为，且它们的长都为，则的长为　 　　　　　　　．

13．命题 “存在xR，使得”的否定是：　　　　　　　　　 ．