根据短文理解, 从A、B、C、D四个选项中选择最佳答案填空。
There are robots all around us. Some do very 1 jobs like flying planes and driving subway trains. And some do simple jobs.
When an automatic自动的) washing machine 2 , water goes in. The machine wait until the water is hot 3 washing the clothes. It does this by "feedback(反馈)". Information about what's happening is fed back into the robot to tell it 4 to do next.
Our eyes, ears and other senses are our feedback. They tell us 5 around us. So robots are like people in 6 ways. They work and they have feedback.
But 7 robots look like people. Many are hidden away. Robots control the temperature o f our houses, our cookers, our hot water systems. We can set the controls to the temperature we want. The robot does 8 . Its feedback usually comes from a thermostat（自动调湿器）.
One kind of thermostat is a strip(细长片) of metal, which bends(弯曲) when it gets hot. At the right temperature, it bends just enough to work a switch. This turns 9 the heat. As the air around it gets 10 , the metal gets straight, and this turns the heat on again.