信号机制是解决进程同步和互斥的有效工具。实现进程间的互斥时，_爱下问搜题

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问题单项选择题

信号机制是解决进程同步和互斥的有效工具。实现进程间的互斥时，公用变量信号的初值一般设置为 (18) ；实现进程间的同步时，私用变量初值一般设置为 (19) 。

A．-2

B．-1

C．0或正整数

D．任意数值

答案

参考答案：C

解析：(18)、(19) 实现进程间的互斥时，公用变量信号的初值一般设置为1或资源数目，而实现进程间的同步时，私用变量初值一般设置为0或正整数。

改错题

Xiaoming is used to send a lot of cards to his friends 1.

at new year time. And all his classmates did same. But 2.

on one day he read a report in the newspaper, which said 3.

that cards are made of trees. A large number of cards would 4.

consume a lot of trees but at present more and more trees have 5.

been cut down lead to serious floods in some areas. Xiaoming 6.

felt shocked at the report in the newspaper and realized the 7.

important of protecting trees, and then he shared this report 8.

with their classmates. From now on he decides to send his 9.

wishes to his friends by telephone instead sending cards. 10.

判断题

平地、造田、修渠、打井等农田基本建设用电，执行农业生产电价。