What is the sky？ Where is it？ How bright is it？ What lies above it？ These questions are difficult to answer, aren’t they？

　　Is the sky blue？ The sky has no color. We know that there is air around the world. When planes fly, they need air to lift their wings. Planes can’t fly very high because the air gets thinner when they go up higher. If we go up about 1,200 kilometers from the earth, we’ll find no air there.

　　When we talk about the sky, we usually mean the atmosphere around the earth. It is like a very thick “cover” over the earth and keeps it warm. Without the “cover”, the earth would be a very cold place and nothing could live on it.

　　Looking up above us, you will see the blue sky with white clouds. It is usually light blue, but the sky would be dark blue if you go to the top of the highest mountains. And you will see fewer clouds between you and the sun.

　　And if you sit in a spaceship high above the earth, there is no air at all. The sky would be so dark that its color would be black.

　　Sometimes the sky doesn’t look blue. When the sun rises and falls, you will see red, orange, and other colors in the sky. These are the most beautiful moments of the day.

　　Now you may understand that we see colors because the air scatters (散射) the sunlight. Light travels through the air. Without air, there would be no light and no colors.

1.Planes can’t fly very high because ____________.

A．there is air around the world

B．the air gets thinner when they go up higher

C．it’s warmer in the sky

D．the air gets thicker when they go up higher

2.We can see colors of the sky because ____________.

A．the sun rises and falls every day

B．the sky has lots of colors

C．the air scatters the sunlight

D．the sunlight has many colors

3.Which of the following is TRUE？

A．There is little air without light and colors in the sky.

B．The sky will look red, orange and other colors at noon.

C．The sky has only one color when the sun rises and falls.

D．The sky is dark blue if you go to the top of the highest mountains.

What do you do if you're stranded（处于困境的）on a lonely island? Surely you need to find a way to get in touch with the outside world. Your best chance of doing this is to draw the attention of a passing plane.

　　Body signals（信号）

　　Pilots from different countries understand body signals if they have the correct training. When you wave your arms up and down in a straight line, it means "yes". When you point downwards and swing your arm from side to side, it means "no". If you want the pilot to know that it's safe to land, push your hands out in front of you and bend（弯曲）your knees. If you want to say that it's not safe to land, put your arms in the air and move them to one side.

　　Smoke signals

　　The smoke from a fire can be seen from far away, so it's a good way to draw attention. If the weather is dry, it isn't hard to start a fire. Remember, however, that fires can be very dangerous if they get out of control. Never light a fire unless you're sure that it can't spread. If the ground is dark, light smoke can be seen more easily. Green grass and leaves produce light smoke.

　　Ground-to-air signals

　　It's a good idea to build some signals, too. Use large pieces of wood to make the symbols(标记). If you can't find any wood, use earth. Some useful symbols are:

　　F "I need food and water."

　　II "I need medicine."

　　I "I am badly hurt."

　　X" I am unable to move from here."

　　Pilots' replies

　　If the pilot lowers the plane's wings from side to side, this means "message received and understood". (At night, the pilot flashes the plane's green lights.) If the pilots flies the plane in a clockwise circle, this means "message received but not understood".(At night, the pilot flashes the plane's red lights.)

However, there is no signal which means "message not received". Why not?

1. Which picture means "it's not safe land"?

2. What can we learn from the passage?

　　A. Swinging your arm from side to side means "yes".

　　B. If the ground is dark, light smoke can't be seen.

　　C. If you need some medicine, make a symbol "II".

　　D. The pilots make replies with a blue light at night.

　　3. What is the passage mainly about?

　　A. The explanation of building signals on an island.

　　B. The importance of making signals on an island.

　　C. Ways of sending out signals on a lonely island.

D. Ways of receiving signals from a lonely island

My work keeps me in Hong Kong most of the year，but I try to get away for a month in summer，usually in July．Now as you probably know，that’s the main　1　season in Europe．The favorite places for vacations and the famous cities are usually very　2　． But I’m not seeking(寻求) the sun—I can get lots of 　3　in Hong Kong—and I’m certainly not seeking the crowds！So　4　I go on vacation，I buy a Train Pass(a kind of train ticket) that allows me first-class travel on most of the railways of Western Europe．First-class compartments(车厢) are　5　crowded and they are very comfortable．If you’re going on　6　trip, you can take a sleeping train for an extra charge．There are usually dining cars(餐车) in the train．
I find that train travel is restful and　7　．There’s always　8　to see．I particularly(特别地) enjoy　9　through Switzerland and Italy．You can get a very good　10　of what a country is like from a train because you don’t go too fast and you stop quite often．Also train travel is very safe，and I am never sick on a train　11　I am on a ship. Then there are always people to　12　to if you feel like a chat.
The reason that I seldom(很少) travel by plane is quite　13　: because train stations are usually built in the centre．I don’t have to　14　transport(运输工具), transport can be a problem when arriving by　15　．

My work keeps me in Hong Kong most of the year，but I try to get away for a month in summer，usually in July．Now as you probably know，that’s the main　1　season in Europe．The favorite places for vacations and the famous cities are usually very　2　． But I’m not seeking(寻求) the sun—I can get lots of 　3　in Hong Kong—and I’m certainly not seeking the crowds！So　4　I go on vacation，I buy a Train Pass(a kind of train ticket) that allows me first-class travel on most of the railways of Western Europe．First-class compartments(车厢) are　5　crowded and they are very comfortable．If you’re going on　6　trip, you can take a sleeping train for an extra charge．There are usually dining cars(餐车) in the train．

I find that train travel is restful and　7　．There’s always　8　to see．I particularly(特别地) enjoy　9　through Switzerland and Italy．You can get a very good　10　of what a country is like from a train because you don’t go too fast and you stop quite often．Also train travel is very safe，and I am never sick on a train　11　I am on a ship. Then there are always people to　12　to if you feel like a chat.

The reason that I seldom(很少) travel by plane is quite　13　: because train stations are usually built in the centre．I don’t have to　14　transport(运输工具), transport can be a problem when arriving by　15　．

1.                A．vacation        B．visiting         C．cloudy   D．windy

2.                A．quiet          B．useful          C．exciting   D．crowded

3.                A．pleasure        B．daylight         C．sunshine  D．money

4.                A．when          B．where          C．what D．which

5.                A．always         B．hardly          C．certainly  D．nearly

6.                A．summer        B．overnight       C．day-time  D．vacation

7.                A．cheap          B．expensive       C．interesting D．lonely

8.                A．something      B．nothing         C．anything  D．everything

9.                A．running        B．walking         C．driving   D．travelling

10.               A．view           B．idea           C．seat  D．trip

11.               A．rather than      B．or             C．as    D．even though

12.               A．talk            B．speak          C．tell   D．say

13.               A．easy           B．wrong          C．right  D．simple

14.               A．find out        B．worry about     C．wait for   D．take away

15.               A．ship           B．train           C．air   D．car