阅读下列五个段落，并从所给选项中选出每一个段落最恰当的小标题，并将其字母标号填在相应的横线上（其中一个为多余选项）
F．New "Green" Red Buses 45． What is red but green, open but closed and old but new? Answ  er: London's stunning new double-decker buses．The new bus uses more efficient green technology and has two staircases and an open platform, enabling people to hop on and hop off．It also has a special design for the front end, which gives it a futuristic look．46．______ For many years British people have been advised to eat at least five items of fruit or vegetables every day in order to improve their health and reduce the likelihood of illness, in particular, cancer．However, according to a new scientific study, only 2．5% of cancers could be prevented by eating more fruit and vegetables． 47．_______ American actor Ashton Kutcher is no longer the most popular person on Twitter．With almost five million followers ?about 20,000 more than Ashton, Britney Spears is the most popular person on Twitter now．In reply to the news, Britney tweeted, "WOW!!!!! # 1 on Twitter! Thank you!" and treated fans by answering questions they tweeted to her． 48．_______ According to a report, being away from school for a long time can mean you start to forget what you've learnt during the school year．Researchers say the school year should be divided into five eight-week terms, with only four weeks off for summer,-instead of six weeks．They think that way, you would be more likely to remember things you learnt in subjects like maths and science． 49．_______ Jordan Romero, who is trying to become the youngest ever person to climb the world's highest mountain, has reached the first level．Advanced Base Camp．He's been training hard and his family think that he's ready to do it．However, some people think that he's far too young to be taking on such a dangerous adventure． |