【判断题】推销员介绍产品和示范产品,应该是用专业性语言。( )
【单选题】It's very stupid ____him to laugh ____his sister when she is in trouble .
【多选题】时间数列与变量数列进行对比,以下()属于它们的区别。
【单选题】It's very stupid ___________ you to buy the useless machine ___________ 2000 dollars.
【单选题】时间数列与变量数列进行对比,以下哪项( )不属于它们的区别。
【单选题】It's very stupid _____ you to laugh ______ your sister when she is in trouble.