【单选题】设函数z=f(x,y)具有一阶及二阶的连续偏导数, 为该函数的一个驻点,记 , , ,如果 ,则该函数在P处( )
【单选题】设函数 具有一阶及二阶的连续偏导数, 为该函数的一个驻点,记 , , ,如果 ,而 ,则该函数在点 处
【单选题】电冰箱必须具备保鲜性能,这是对商品质量中( )的基本要求。
【简答题】You will need to keep in touch with the head office of the organization.
【简答题】听力原文:Woman: Are you going to Head Office on Monday? If you are, do you want to go with me? I could pick you up about 8 and we'd be there by 10 if there wasn't too much traffic. What do you say? (19)