A meteorologist conducted an experiment in which the temperature was measured every 3 hours. When measuring the temperature for the twelfth time, how long has it been since the start of the measurement?
气象专家做一项实验，每隔3小时测量一次气温．第十二次测量气温时，距开始测已过多长时间？
<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<gadget id="calculator">3 * 11</gadget>
<output>33</output>

<result>33</result>