听力原文： Junk food, too little exercise and an increasingly sedentary life style, all well-known factors in the spiraling problem of childhood obesity in Britain. The causes are clear, but the government's efforts to tackle the problem are inefficient confused and under-resourced ac-cording to Today's Report. Obesity costs the NHS one billion pounds a year, and blights the health of up to one million children under 16. Doctors say this could be the first generation for decades to die before their parents unless urgent action is taken. Yet, progress is so slow according to Today's Report that the government risks missing its target of halting obesity in children under 11 by 2010. The Health Care Commission, Audit Commission and National Audit Office're pointing out it's taken 31 experts 18 months to agree how to measure obesity. The report says there are many initiatives to tackle the problem, but no specific funding. It complains that many organizations involved are unclear about their roles, causing potential confusion and wasting resources. And it adds that there are too few frontline staff to deal with the complex problem of obesity. According to the passage, what cause(s) the problem of childhood obesity in Britain?