What is the main difference between CD$-$ROM, in$-$house and onling

Correct or wrong these sentences or phrases? Select only $5$ of these?

A$.$ There are different kinds of cross$-$references in Subject Heading List: those preceded by BT are of equal or narrower scope, and those preceded by NT are more general?

$x$

B$.$ A book is a work that consists of written or printed pages that are bound together at more than one edge and covered with a unprotective cover.

C$.$ Should the library convert the vertical file contents to digital files?

D$.$ Video materials means: images, films and other visual material ari preserved on videocassettes, musical and spoken records are preserved on records, audio cassettes?

$x$