某书店有一个收银员，该书店最多允许n个购书者进入。将收银员和购书者看做不同的进程，其工作流程如图5-3所示。利用PV操作实现该过程，设置信号量S1、S2和Sn，初值分别为0、0和n。则图5-3中a1、a2、b1和b2应分别填入(26)。

ASCII　is　a　7-bit　code　used　to　represent　numeric,　alphabetic,　and　special　printable　characters.　It　also　includes　codes　for　control　characters,　which　are(75).

How　many　key　comparisons　are　needed　in　searching　for　key　value　38?(74).

The　error　messages　given　by　a　C　compiler　show　the　message　text,　the　most　common　cause　of　the　error,　and　a　suggestion　for(73)the　error.

Transport　gateways　connect　byte　streams　in　the　transport　layer.　Application　gateways　allow　interworking　above(72).

What　is　the　decimal　value　of　tile　binary　value　100107(70).

By　means　of　multiple　pipeline　to　carry　out　multiple　processing,　this　technology　is　called(71).

An　instruction　that　uses　indrect　addressing　mustt　contain　an　address　of　memory　where(69).

In　which　phase　of　the　software　engineering　process　is　the　Software　Requirements　Specification　developed?(68).

The　sorting　method　described　by　the　code　is　called(67).

In　a　computer,　if　a　logical　left　shift　of　the　operand　occurs,　its　lowest　bit　is(66).