WebSQL is a SQL-like (26) language for extracting information from the web. Its capabilities for performing navigation of web (27) make it a useful tool for automating several web-related tasks that require the systematic processing of either ail the links in a (28) , all the pages that can be reached from a given URL through (29) that match a’ pattern, or a combination of both. WebSQL also provides transparent access to index servers that can be queried via the Common (30) Interface.

A．Router

B．Device

C．Computer

D．Gateway

超声灰阶断面图像的伪影有（）

A.部分容积效应

B.折射声影

C.声速差异伪像

D.旁瓣伪影

E.混响