题目内容：

请阅读下面趣味实验，根据情境先将A、B、C、D四个句子填入第31-34小题中，以便顺利进行该实验；然后完成第35小题。

Reading this message may need a special trick. Here is how you can make the words appear.

You’ll need:

● Half of a lemon

● Cup or small glass with four table spoons of water in it

● Cotton swab (棉签)

● White paper

● Electric lamp

● Milk

You’ll do:

31. ________→32. ________→33.________→34.________

What happens?

Lemon juice is clear, but it contains chemicals that are partly made of carbon (碳). The chemicals break down when they are heated and the carbon causes them to change color.

 

A. Hold the paper close to the light bulb to heat it. You can see the writing now.

B. Dip the swab into the juice and water mixture and write some words on the paper.

C. Squeeze (挤) some lemon juice into the water and mix them.

D. Let the paper dry. Show it to someone and ask if he or she can see a message on it.

A. Hold the paper close to the light bulb to heat it. You can see the writing now.

B. Dip the swab into the juice and water mixture and write some words on the paper.

C. Squeeze (挤) some lemon juice into the water and mix them.

D. Let the paper dry. Show it to someone and ask if he or she can see a message on it.

 

1.______

2.______

3.______

4.______

5.Which of the following can be the best title?

A. Perfect messages. B. Pleasant messages.

C. Important messages. D. Invisible (看不见的) messages.