AT89S51单片机响应外部中断的典型时间是多少？在哪些情况下，CPU将推迟对外部中断请求的响应？

AT89S51的异步通信口为（）（单工/半双工/全双工）

Project（71）is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

Project ______is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

● Project（71）is an uncertain event or condition that, if it occurs, has a positive or a negative effect on at least one project objective, such as time, cost, scope, or quality.（71）

AT89S51单片机为（）位单片机

AT89S51单片机芯片共有（）个引脚，MCS-51系列单片机为8位单片机。

AT89S51单片机为（）位单片机，共有（）个引脚

当AT89S51单片机复位时，下面说法正确的是（）。

AT89S51单片机不论是进入空闲模式还是掉电运行模式后，片内RAM和SFR中的内容均保持原来的状态。

Every deliberate act of wrongdoing by the master or any of the crew against the ship or cargo，without the authorization or privity of the Shipowner or his agent，is（）.

A mark or place at which a vessel comes under obligatory entry，transit，or escort procedure is know as（）.