纸筋灰中的纸筋的作用是( )。

A．提高水泥砂浆的强度

B．提高石灰膏的抗裂性

C．提高石灰膏的强度

D．提高石灰膏的和易性

Because Web servers are platform and application (17) ，they can send or request data from legacy or external application including database．All replies，once converted into (18) mark up language，can then be transmitted to a (19) ．Used in this way，Intranets can (20) lower desktop support costs，easy links with legacy application and databases and， (21) all。ease of use．

A．ciphertext
B．hypertext
C．plaintext
D．supertext