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.

Dear friends,

I’m Xiaofei—on Douyin. Welcome to cook with me. Today I want to show how to make my favorite salad.

My dear mom passed down this recipe(食谱). It is called Ambrosia Salad, and it’s also my family’s favorite.

First, choose your favorite fruit. Use fruit in season. Make sure it is fresh. Besides, use fruit of different colors and try to make your fruit salad look as good as it tastes. For example, mixing apples, green pears, purple grapes and oranges together will make the salad look very colorful. I think the strawberries are a great addition! I especially like this in spring!

Then, put some salad dressing and mix the fruit and salad dressing together. If you want to give a special taste to your salad, you can also put in a quarter cup of peanut which is cut into pieces.

Make the fruit salad just before you are going to eat it. Some of the fruit will quickly turn brown when you leave it in the air for some time.

Don’t wait anymore, and try to do it yourself. If you like this recipe, please give me 5 stars.

1.What does Xiaofei want to do?

A.Teach people to make salad. B.Sell family salad on Douyin.

C.Give advice on choosing fruit. D.Show how delicious the salad is.

2.Which can give a special taste to your salad?

A.Peanut pieces. B.Fresh strawberries. C.Green pears. D.Purple grapes.

3.Which of the following sentences is true?

A.You must use the fruit listed.

B.Salad dressing makes the salad colorful.

C.Choose your favorite fruit to make the salad fresh.

D.You’d better not leave the salad in the air for long.

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