WebSQL is a SQL-like （） language for extracting information from the web. Its capabilities for performing navigation of web （） make it a useful tool for automating several web-related tasks that require the systematic processing of either all the links in a（） , all the pages that can be reached from a given URL through （） that match a pattern, or a combination of both. WebSQL also provides transparent access to index servers that can be queried via the Common （） Interface.

all the pages that can be reached from a given URL through （） that match a pattern.

A．paths

B．chips

C．tools

D．directories

下面关于8237可编程DMA控制器的叙述中，错误的是()。

A．两个8237级联可以得到8个DMA通道

B．8237的数据线为8位

C．每个通道有硬件DMA请求和软件DMA请求两种方式

D．每个通道在每次DMA传输后，其当前地址寄存器的值自动加1或减1