CA

A transport layer protocol usually has several responsibilities．One is to create a process-to-process communication；UDP uses (71) numbers to accomplish this．Another responsibility is to providecontrol mechanisms at the transport level．UDP does this task at a very minimal level．There is no flowcontrol mechanism and there is no (72) for received packet．UDP, however,does provide errorcontrol to some extent．If UDP detects an error in the received packet，it will silently drop it．
The transport layer also provides a connection mechanism for the processes．The (73) must be able to send streams of data to the transport layer．It is the responsibility of the transport layer at (74) station to make the connection with the receiver,chop the stream into transportable units，numberthem，and send them one by one．It is the responsibility of the transport layer at the receiving end to waituntil all the different units belonging to the same process have arrived，check and pass those that are (75) flee，and deliver them to the receiving process as a stream．

A．connection

B．window

C．acknowledgement

D．destination

某男，20岁，农民，发热2周于7月20日入院，体温39．2℃，精神稍差．腹部5个小出血点，腹胀，脾侧位可及．血WBC4．1×10⁹/L，本患者最大可能的诊断是（）

A.钩体病

B.伤寒

C.斑疹伤寒

D.结核病

E.流行性出血热

我国政府宏观调控和应对复杂局面能力( )。

A．有所提高
B．有些提高
C．提高不大
D．明显提高

楼梯是由( )组成的。

A．梯段

B．平台

C．栏杆扶手

D．楼梯井

E．梯段高度

锂盐对情感障碍复发的预防作用较安慰剂高( )

A．2倍
B．3倍
C．4倍
D．5倍