阅读古代诗歌,回答问题
悲陈陶①
杜甫
孟冬十郡良家子,血作陈陶泽中水。
野旷天清无战声,四万义军同日死。
群胡归来血洗箭,仍唱胡歌饮都市②。
都人回面向北啼,日夜更望官军至。
注:①陈陶:地名,在长安西北。公元756年唐军跟安史叛军在此交战,几乎全军覆没。②都市:指唐都城长安。
How often do you use your car? Can you use your car less often? Do you know the following facts in the UK?·About 50% of all car journeys are just for fun.·Over 80% people go to work by car.·25% car journeys are under two miles.·70% car journeys are under five miles.WALKING & CYCLINGInstead of using the car for short journeys, why not walk or ride a bicycle? Walking is the most popular form of exercise—it’s healthy and it can save money. If you work nearby, try walking or cycling instead of driving. Walking your children to school gives them valuable road experience.BUSESBus companies are using new buses: some run on new fuelswhich produce less pollution; some have easier access(通路)for disabled and old people. There are special traffic lanes (行车道)to make bus journeys easier. So do something to help solve the pollution problem----let the bus take you to work and your children to school.TRAINSAll car journeys, long or short, can be hard work. For some trips, it is wiser to take the train. Leave your car at home and walk, cycle or take a bus to and from the station. Train travel is fast, safe and comfortable. Train tickets are not always expensive.
如图,⊙O的直径AB=10cm,弦CD⊥AB,垂足为P.若OP︰OB=3︰5,则CD的长为 ( )