下引线是指在K线图中，从开盘价到收盘价之间的线段，通常表示股票价格在一定时间段内的下跌。下引线的长度表示下跌的幅度，下引线越长表示下跌幅度越大。

在技术分析中，下引线通常被认为是卖出的信号。当股价在一定时间内连续出现下引线时，这通常表明市场正在积聚卖压，这可能导致股价进一步下跌。因此，技术分析师可能会建议投资者在出现下引线时卖出股票。

然而，也有一些投资者认为下引线可能是买入的信号。他们认为，当股价在一定时间内连续出现下引线时，这可能表明市场正在形成底部，这可能导致股价在未来上涨。因此，他们可能会选择在出现下引线时买入股票。

总之，下引线的意义取决于投资者对市场的看法和投资策略。对于技术分析师来说，下引线通常被认为是卖出的信号，但对于一些投资者来说，下引线可能是买入的信号。投资者应该根据自己的投资目标和风险承受能力来制定投资策略，并密切关注市场动态和相关指标，以便更好地把握买卖时机。

In English:

The lower shadow refers to the line segment between the opening price and the closing price on the K-line chart, which usually represents the decline in stock prices within a certain time period. The length of the lower shadow represents the magnitude of the decline, and the longer the lower shadow is, the larger the decline is.

In technical analysis, the lower shadow is usually considered a sell signal. When the stock price consecutively forms lower shadows within a certain time period, it usually indicates that the market is building selling pressure, which may lead to further declines in stock prices. Therefore, technical analysts may recommend investors to sell their shares when lower shadows appear.

However, some investors believe that lower shadows may be a buy signal. They believe that when the stock price consecutively forms lower shadows within a certain time period, it may indicate that the market is forming a bottom, which may lead to future stock price increases. Therefore, they may choose to buy shares when lower shadows appear.

In summary, the significance of lower shadows depends on investors' views of the market and investment strategies. For technical analysts, lower shadows are usually considered sell signals, but for some investors, lower shadows may be buy signals. Investors should develop investment strategies based on their investment goals and risk tolerance, and closely monitor market dynamics and relevant indicators to better grasp buying and selling opportunities.