Can you think of any questions，you have about the natural word？By trying to find the answers to you questions，you are acting like a scientist．

Why does the sky look blue on a sunny day？Sunlight made up of red orange．yellow．green．blue，indigo （靛蓝） and violet （紫色）light．The air is made up of many tiny bits （小块）．Most colors in the light move directly through the air．The blue and indigo parts of the light bump into （碰撞） the bits of air．The light spreads out and makes the sky look blue．Light can make a glass of milk look blue，too．

Let's Do it!

☆Fill a glass partway （部分）with milk．

☆In a dark room，shine a flashlight（ 手电筒）into the top of the glass of milk．

☆What happened？The glass looked blue because the bits that made up the milk took in （吸入） the red．orange．yellow．Green and violet colors but not the indigo and blue colors in the light．Instead the milk pushed the blue light to the sides．

Keep looking at the world like scientist．Just star with a question and try to find the answer．You are sure to uncover lots of fun facts about the natural word．No matter what you want to find out next．Remember to have fun．Learning about the word can be a lifelong（终生的）adventure．

41．You can act like a _____by trying to find the answers about the natural word． 　　

A．	violinist
B．	scientist
C．	policeman
D．	teacher

42．Sunlight is made up of _____ kinds of light． 　　

A．	five
B．	six
C．	seven
D．	eight

43．what makes a glass of milk look blue？ 　　

A．	Light
B．	Air
C．	Milk
D．	Glass

44．The bits of the milk take in all the colors except for． 　　

A．	orange and yellow
B．	violet and indigo
C．	green and blue
D．	indigo and blue

45．We can learn from the last paragraph that． 　　

A．	we should try to find the answers with the help of the scientists．
B．	because you are scientists．you have to uncover the facts．
C．	no matter whether you are young or old．Try to learn about the natural world．
D．	if you want to have fun．keep looking at the world like a scientist．