※ [1～5]( ) . ( 3 ) ( ) . A． B．

(31)～(35)题使用下列数据表。
部门 (部门号C(2)、部门名称C(10))
职工 (部门号C(2)、职工号C(4)、姓名C(8)、基本工资N(7,2))

为“部门”表增加一个“人数”字段，类型为整型，正确的命令是( )。

A．ALTER TABLE 部门 ALTER 人数 I

B．ALTER TABLE 部门 ALTER FIELDS 人数 I

C．ALTER TABLE 部门 ADD 人数 I

D．ALTER TABLE 部门 ADD FIELDS 人数 I

A glue that holds the whole Internet together is the network layer protocol, (1) .Unlike most older network layer protocols, it was designed from the beginning with internetworking in mind. Its job is to provide a (2) way to transport data grams from source to destination, without regard to whether these machines are on the same network or whether there are other networks in between them.

Communication in the Internet works as follows. The (3) layer takes data streams and breaks them up into data grams. Each datagram is transmitted through the Internet, possibly being fragmented into smaller units as it goes. When all the pieces finally get to the destination machine, they are reassembled by the (4) layer into the original datagram. This datagram is then handed to the transport layer, which inserts it into the receiving process’ input stream.

An IP datagram consists of a header part and a text part. The header has a (5) part and a variable length optional part.

3（）

A．data link

B．transport

C．network

D．application

Ollier病属于

A．骨组织肿瘤

B．软骨组织肿瘤

C．纤维组织肿瘤

D．骨髓组织肿瘤

E．滑膜组织肿瘤

国际放射界公认的人眼模糊阈值是（）

A.0.2mm

B.0.4mm

C.0.6mm

D.0.8mm

E.1.0mm

一般来说企业利润达到最高水平是在产品生命周期的（）.

A．介绍期 

B．成长期 

C．成熟期 

D．衰退期