已知x，y是互为相反数，且满足等式3x+5y=9，则x=（ ）y=（ ）。
；。
—We'll go to Qing Yuan Mountain tomorrow. Why _ _ join us?
—That's a good idea. [ ]
A. not
B. don't
C. can't
D. didn't
骨干NGN网络的考核指标是：（）。
A.目的码应试比
B.网络接通率
C.应占比
D.接通率
；
。
；。