题目

Growing up, your mom probably kept telling you that you should make your bed in the morning. But it’s time to put this little habit to rest. In fact, it could be better for your physical health to leave your bed unmade during the day, experts say.What allows you to be extra lazy? Dust mites (尘螨). These little creatures live on our dead skin and produce allergens that you could breathe in while you are sleeping. And about 1.5 million dust mites are spending every night with you right now. Thankfully, there’s an easy way to get rid of them: Don’t make your bed in the morning.Researcher如图所示，电源电压为6V，电路中的三只灯泡相同，当开关S闭合时，电压表的读数为    V；当开关S断开时，电压表的读数为    V．