WebSQL is a SQL-like （1） language for extracting information from the web. Its capabilities for performing navigation of web （2） make it a useful tool for automating several web-related tasks that require the systematic processing of either all the links in a（3） , all the pages that can be reached from a given URL through （4） that match a pattern, or a combination of both. WebSQL also provides transparent access to index servers that can be queried via the Common （5） Interface.
（3）处填（）。
A．hypertext
B．page
C．protocol
D．operation
