套利交易指的是在买入或卖出某种期货合约的同时，卖出或买入相关的另一种期货合约，并在某个时间同时将两种合约平仓的交易方式。（）
参考答案：对
It is politely requested by the hotel management that radios __________ after 11 o'clock at night.[ ]
A. were not played
B. not be played
C. not to play
D. did not play
下列有关“非梗阻性胃扩张”原因中，错误的是()
A．用吗啡制剂
B．尿毒症昏迷
C．糖尿病胃病
D．急性腹膜炎
E．先天性肥厚型幽门狭窄
