A buzzer sounds every 15 minutes．If the buzzer sounded at 12:40，which of the following could be a time at which the buzzer sounded（） A: 4:05 B: 5:30 C: 6:45 D: 7:15 E: 8:10

proteus软件中常用BUZZER

digitalWrite(Buzzer,HIGH)语句的含义（）。

Suppose you are riding on a hot air balloon, carrying a buzzer that emits a sound of frequency f . If you accidentally drop the buzzer over the side while the balloon is rising at constant speed, the frequency and intensity of what you can hear sound as the buzzer falls toward the ground ___________ and __________ respectively. (fill in increases/decreases and use the comma to connect two choices)

To _____ the ambiguity of a horn or buzzer, a voice message system is used in most airliners.

As a result the nerves of both the Duke and Duchess were excessively frayed when the ______ buzzer of the outer door eventurally sounded.

以下说法错误的是void main(){ state=1; while(1) { switch(state) { case 0x01:setup();break; case 0x02:run();break; } }}void setup(){ Buzzer=1;Led=1;while(1) { if(Key==0){state=0x02;goto exit;} }exit:return;}void run(){ Buzzer=0;Led=0; while(1) { if(Key==0){state=0x01;goto exit;} } exit:return;} A: 共有两个状态 B: Buzzer=1;Led=1;实现声光报警 C: Buzzer=1;Led=1;全停 D: if(Key==0){state=0x01;goto exit;} 按下按键，转到第一个状态

To _____ the ambiguity of a horn or buzzer, a voice message system is used in most airliners. A: prevent B: abolish C: cancel D: eliminate

_______源蜂鸣器的BUZZER是_______蜂鸣器。 A: 有；通用 B: 无；通用 C: 无；非通用 D: 有；非通用

中国大学MOOC: As a result the nerves of both the Duke and Duchess were excessively frayed when the muted buzzer of the outer door eventually sounded. (Para. 1)