宁夏“沙湖”是闻名全国的五A级旅游胜地．当你在烈日当空的“沙湖”游玩时，你会发现

-_________dress is it?

-It's my mother's.[ ]

A. What  

B. Who    

C. Whose

持票人对前手的再追索权， 自清偿或者被提起诉讼之日起 ( )。

A．3个月

B．6个月

C．2年

D．5年

One of the difficulties in building an SQL-like query language for the Web is the absence of a database （） for this huge, heterogeneous repository of information. However, if we are interested in HTML documents only, we can construct a virtual schema from the implicit structure of these files. Thus, at the highest level of （） , every such document is identified by its Uniform Resource Locator (URL), has a （） and a text. Also, Web servers provide some additional information such as the type, length, and the last modification date of a document. So, for data mining purposes, we can consider the set of all HTML documents as a relation: Document(url, title, text, type, length, modif)Where all the （） are character strings. In this framework, an individual document is identified with a （） in this relation. Of course, if some optional information is missing from the HTML document, the associate fields will be left blank, but this is not uncommon in any database.

an individual document is identified with a （） in this relation

A．relation

B．field

C．script

D．tuple

基2FFT算法计算N=2^L（L为整数）点DFT需（）级蝶形，每级由（）个蝶形运算组成。

看图计算内六角筒的展开尺寸，（长为S，宽为H）已知δ=2毫米，边长ａ=20毫米，六角筒高h=35毫米。