Web pages are viewed with（）.

单项选择题When you move the mouse pointer to a（），the pointer’s shape usually changes to a pointing hand.

A.hyperlink
B.selected text
C.selected graphic
D.web page

单项选择题（）is a copy of a file for use in the event of failure or loss of the original.

A.second storage
B.buffer
C.backup
D.database