narrative: I once took apart an old thermostat. It was a very simple device with mercury held in a glass tube. Mercury changes density very easily. That is why it is used for thermostats. I put the thermostat back together when I was done.
question: Why was It a very simple device with mercury held in a glass tube?
original_sentence_for_question: It was a very simple device with mercury held in a glass tube.
answer: it was an old thermostat.
original_narrative_form: I once took apart an old thermostat. It was a very simple device with mercury held in a glass tube. Mercury changes density very easily. That is why it is used for thermostats. I put the thermostat back together when I was done.
question_meta: rocstories_narrative_22117_sentence_1_question_0