若3xm+1y2与x3yn的和是单项式，则m+n=（ ）。
4
35．—Oh，I just realized that I don’t have any money．
—You don’t？Well，don’t worry，I________lend you some．
A．will
B．should
C．am going to
D．am to
METROSITE基站最多可以安装（）个载频？
A.4
B.6
C.8
D.12
