题目内容：

    Infrared thermometers（红外温度计）, or temperature guns, have been widely used to detect（检测）the early symptoms of COVID-19. They allow us to measure（测量）temperatures quickly. How do these thermometers work?

They determine temperature by measuring the energy coming from your skin （皮肤）. Everything in nature has molecules （分子） inside of it that are always moving around. This include our skin. The higher the temperature is, the faster the molecules move. The molecules give off infrared light while moving.

This kind of light can be focused or absorbed（吸收）. The thermometers use a lens（镜头）to focus infrared light from the skin onto a detector called a thermopile（热电堆）. The thermopile absorbs the infrared radiation and turns it into heat. The electronic sensors inside the thermometers can measure the heat and read the temperature of the skin after making some calculations （计算）.

However, you might sometimes find that the results aren’t always accurate （准确的）. It depend on how these devices are used. For example, how far away they are held from the body, how steadily they are held and for how long. Factors such as make-up and sweat will also affect the results.

1.Temperature guns, have been widely used to detect （检测）the early symptoms of____________.

A.COVID-17. B.COVID-18. C.COVID-19. D.COVID-20.

2.They determine temperature by measuring the energy coming from your____________.

A.skin B.head C.face D.foot

3.The electronic sensors inside the thermometers can measure the heat and read the____________ of the skin.

A.color B.temperature C.light D.structure

4.Which one of the following might not affect the accurate results?

A.The thermometers is too far from the body.

B.The thermometers is held for very long.

C.Make-up and sweat.

D.The thermometer is held steadily at the right time.