underlying economy好像应该是指股票市场相对的经济，美国股市相对美国经济，中国股市相对中国经济的意思，这里意思是说如果是在美国，估价和历史趋势以及相对应的经济形势不符合的时候，通常是人们担心所在。

valuations that seem out of step with historical trends (and, in America, the underlying economy) are usually ones to worry about.

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实证结果表明在中国股票市场中信息交易概率与市场流动性正相关，而与波动性负相关，进一步揭示了中国股市的价格行为。

The results show that higher PIN leads to (lower) (liquidity) and higher volatility and vice versa. At the same time these concludes disclose the behavior of the price (further) in China stock market.

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