一朵典型的花包括花梗、花托、花萼、花冠、雄蕊和雌蕊等部分。

涵洞净空高度指洞内顶点到（）的距离。

A、计算水位

B、洞内底部

C、基础顶面

D、基础底面

某幅图像具有640×480个像素点，若每个像素具有8位的颜色深度，则可表示(a)种不同的颜色，经5:1压缩后，其图像数据需占用(b)(Byte)的存储空间。

A．8
B．256
C．512
D．1024

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

园路多是硬质材料铺装，一般由（）三部分组成。

A、路基、

B、路面、

C、道牙，

D、土方

E、块石

船舶航向稳定性与船体水下侧面积形状分布和纵倾情况有关：（）.

A.船尾钝材、尾倾越大，航向稳定性越好

B.船首钝材、尾倾越大，航向稳定性越好

C.船首钝材、首倾越大，航向稳定性越好

D.船尾钝材、首倾越大，航向稳定性越好