The firebell sound cycles three-fourths of a second on, followed

The firebell sound cycles three-fourths of a second on, followed by ten second off for a fire warning. The above sentence means "火警铃声是从一秒的3/4开始响起，紧跟着是10秒的停止这样一个循环来发出火警警告。"

A.1

正确答案是A