Strong demand for cheap exports is driving economic growth in China China's trade surplus neared record levels in February - fuelling criticism that its currency is undervalued.The surplus hit $23.8bn (£12bn) for the month, more than nine times higher than a year earlier and the second largest on record, official data shows. China has resisted calls from the US to remove currency controls that limit the amount the yuan can rise or fall. The US argues that China keeps the yuan artificially cheap in order to boost its exports. According to Goldman Sachs analysts "the significant increase in the...