在QoS部署方案中，优先在CE业务侧端口进行（）IPP业务标识。
A.二层
B.三层
C.四层
D.五层
参考答案：B
根据下面对话中的情景，在空白处填入适当的句子
A: Hi, Frank. Look at this photo.
B: Oh, it's a family photo. (1)__________.
A: Yes, it is my mother.
B: (2)__________.
A: Yes, ts ry father.
B: Who's this?
A: Guess(猜)!
B: Is it your sister?
A: (3)__________.
B: And (4)__________ your brother?
A: No. it isn't.
B: Ha! Hal It's you.
A: Yes! (5)__________.
套利的潜在利润基于价格的上涨和下跌。( )
