詞匯: 增長（更大和更老） Vocabulary: growing

As China's economy has grown bigger, its population has grown older. But is China growing too old, too fast?

The one-child policy has caused a decline in the birth rate, while the average age has gone up. One in four permanent residents in Shanghai is retired, and the rest of China will soon be just as mature. The Chinese population is no spring chicken: by the year 2050, a third of Chinese people will be over the age of 60.

A demographer from Fudan University said that "the speed of ageing in China is unique." It has only taken China 20 years to reach an age profile that took Britain or France 60 or 70 years.

But what problems are associated with living until a ripe old age? Fewer than 2% of the elderly will find a place in a state nursing home because all the beds are taken up.

China's economy also depends on a supply of cheap, young workers – and this supply is running out. "You can see the way an ageing society is affecting the labour force" says Jerry Mo, owner of a small factory. "We are becoming unprofitable."

An ancient Chinese saying sums up why this challenge is so worrying: China will become "too old to get rich." Despite its booming economy, China is still a developing country. Can it find solutions as quickly as new challenges are born?