21．Twenty-four trains，nine countries，13，500 miles.
They are the numbers behind a train journey one man took from Southampton in the UK to eastern China.Roger Tyers，37，spent a month on board trains and over ＄ 2，500 — almost three times the cost of a return flight to travel to the Chinese port city Ningbo for academic research in May，2019.It was the climate crisis that drove this socialist to choose this complex route.Tyers told CNN that he felt it necessary to stop flying when UN climate experts warned last year that the world has less than 11 years to avoid disastrous levels of global warming.
Tyers is not the
sole person to avoid air travel in response to climate change.Thousands of people worldwide have publicly promised to stop flying，including teenage activist Greta Thunberg，who has inspired youth climate protests around the world.Activist Maja Rosen started the "Flight Free" campaign in Sweden in 2018 with the aim of encouraging 100，000 people not to fly for one year.
Rosen，who stopped flying 12 years ago，says the "Flight Free" campaign helps fight the sense of hopelessness many people feel when it comes to dealing with climate change. "One of the problems is that people feel there's no point in what you do as an individual.The campaign is about making people aware that if we do this together，we can actually make a huge difference，" she said.
A passenger's footprint from an individual flight depends on a number of factors，including how far he flies，how full the plane is，and what class he travels in：First class passengers are given more space than economy passengers，meaning they're responsible for a bigger part of the plane's emissions.Tyers said that his train journey to China produced almost 90% less emissions than a return flight.
（1）What made Tyers go to China by rail？ （no more than 5 words）
（2）What does the underlined word "sole" in Paragraph 3 probably mean？ （1 word）
（3）According to Rosen，what can people realize through the "Flight Free" campaign？ （no more than 15 words）
（4）What affects passengers' footprint from a flight？ （no more than 10 words）
（5）What inspiration can you get from Roger Tyers' story？ （no more than 25 words）
