K-means算法叙述正确的是（）

A:在K-means算法中K是事先给定的，这个K值的选定是非常难以估计的 B:在K-means算法中，首先需要根据初始聚类中心来确定一个初始划分，然后对初始划分进行优化 C:对于一个类中的每个对象，在其给定半径的领域中包含的对象不能少于某一给定的最小数目 D:从K-means算法框架可以看出，该算法需要不断地进行样本分类调整，不断地计算调整后的新的聚类中心，因此当数据量非常大时，算法的时间开销是非常大的

MEANS是( )

A:过程名 B:关键字 C:变量名 D:文件名 E:字段名

By mentioning Internet, the author means that

A:we are always online and always connected. B:the wireless technology will be popularized as the Internet. C:the Internet will be wireless soon. D:the wireless technology will become a monopoly.

DAF means Delivered At( )．

A:Foreign B:Freight C:Full D:Frontier

DAF means Delivered At ( ).

A:Foreign B:Freight C:Full D:Frontier

"The term ANCHOR DRAGGING means ______．

A:the normal swinging around the mooring as the tide or wind changes B:an untoward movement of the anchor C:the ship being washed ashore D:the ship being pulled along with difficulty or effort by another ship"

"Extremis situation means________．

A:lose quarters B:immediate danger situation C:very danger situation D:the situation that you shall call the master"

"The word KEY means ______．

A:laden B:small C:pivotal D:big

Windward means:

A:direction to wind B:direction against wind C:wind direction D:variable direction