在CDMA系统中，反向闭环功率控制信噪比门限是根据（）参量的测量统计结果进行调整的。
A.FER
B.C/I
C.RSSI
D.Eb/Nt
参考答案：A
The exhibition is well worth _____ and you can see fancy vases of different dynasties on show there.
A．to visit
B．to be visited
C．being visited
D．visiting
设D=(x，y)|-1≤x≤1，0≤y≤2，则二重积分I=
=______．
=______．