产生弯曲损耗的原因是（）使光能损耗。
参考答案：模式转换
Mom，I lost ________ diamond ring you bought for me as my birthday present. Could you keep ________ eye out for it when you clean my bedroom?[ ]
A．a；an
B．a；the
C. the；an
D．the；the
H248协议的端口号是（）
A、1501
B、8888
C、2944
D、8080
