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When the traffic lights turn red, we will stop driving a car or crossing a street. Why is red used for traffic lights instead of other colors?
As we know, scattering (散射) happens when light goes through the air. For the same media(媒质), if the wavelength is long, the scattering will be short. If the wavelength is short, then the scattering will be long.
Of all lights we can see red has the longest wavelength, so the scattering is the weakest. That means the red light travels far. In fact, it travels farther on rainy days.
Using the red light can help drivers in farther areas sec the lights. It helps drivers stow down or stop in lime. If drivers don't see the red light until they are close, they may not be able to stop the car in time. An accident may happen Red can also excite people. We can act more quickly when we see the color red. In a word, red lights help drivers stop in time and help prevent accidents.
1. When the traffic lights turn ______, we will stop driving a car.
A. red B green C. yellow
2.According to the passage, the scattering of the red light is the _______.
A. longest b. weakest C. farthest
3. The underlined word "wavelength" means________ in Chinese.
A.波浪 B.光波 C.波长
4. What can the red light help drivers do?
A. It can help drivers in farther areas see the lights.
b. It can help drivers slow down or stop in time.
C. A and b
5.Which of the following is the best title?
A. Why do accidents happen
b. How does the red light travel
C. Why do we use red traffic lights
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阅读下面对话，从方框内7个选项中选择5个恰当的句子完成此对话，并将其番号填到横线上。
A. How time flies!
B. With sugar?
C. Make yourself at home, please.
D. How do you like it?
E. What’s it like?
F. Your hair used to be short,
G. Would you like to drink with me?
Susan invites her old friend Amy who she hasn’t seen for 10 years to her house.
Now Amy is knocking at the door.
A: Hi, Susan. It’s me.
B: Oh, is that you, Amy? Come in please. ??? 1.
A: Thanks. I haven’t seen you for a long time. You have changed a lot.
B: Yes. You too. ??? 2.? Ten years has passed since we met last time.
A: You used to be a little baby fat. But now you look perfect. ??? 3.? but now you have long curly hair.
B: ??? 4.
A: Great. This hairstyle looks quite nice on you. Pretty and smart.
B: Thanks. Forgive me. I am so excited that I nearly forget anything else. Anything to drink?
A: Coffee please.
B: ??? 5.
A: No, thanks. I like it with nothing in it.
B: Just a minute. It will be ready soon.
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A: Hi, Han Mei! What are you doing now?
B: I’m studying for tomorrow’s test. What about you?
A: I’m learning English by l 81 to the tapes. Can you tell me how you learn English?
B: I learn by practicing conversations with my partner.
A: That’s a good idea. I think it can i 82 your speaking skills. Who’s your partner？
B: Liu Ying, one of your classmates at primary school.
A: Oh, wow! It’s her! I remember she u 83 to be short and be very quiet.
B: But now she’s much 84 than before and very outgoing.
A: By the way, do you have lots of rules at school?
B: Yes, we do. For example, we must w 84 uniform at school.
A: Should students be allowed to have part-time job?
B: No. But I think it is necessary for students to have s 85 rules at school.
A: That’s right.
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用恰当的短语或句子补全对话。
A.Zhu ,is that you?
B.Yes You’re Chen,_________ 1______________?
A.Yes ,that’s right ._________2________________.
B.Really?How?
A.You used to be short.Now you’re tall.
B.Yes,I am.
A.__________3_____________.Now you have short hair.
B.Yes,that’s right.
A.And you used to ________4______________.
B.Yes,,I still do.But today I have contact lenses
A._________________5____________, didn’t you?
B.No ,I played the piano .My friend Xiao Li played the guitar.
A.Oh ,yes.I forgot.
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