请写两个对角线互相垂直的四边形______．
对角线互相垂直的四边形有：菱形，正方形．
故答案为：菱形，正方形．
Don't go out on the thin ice, _____ you'll fall in the river. [ ]
A. and
B. but
C. so
D. or
保安员有什么职权？
