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?
【小题1】 Which picture means "it's not safe land"?

　
【小题2】 What can we learn from the passage?

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　．