The -e flag to the echo command tells it to expand C-style escaped characters; in this case, it's going to turn \ t into a TAB character for you.

echo命令的- e标志用来告诉该命令扩展c风格的转义字符，在本示例中，它会把\ t转换为制表符。

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Methods The manifestation, internal echo, the L/T ratio, CDFI and RI frequency spectrum feature of the superficial lymph nodes were studied with high frequency and color Doppler ultrasound 89 cases.

方法本组89例，应用高频率的彩色多谱勒超声检查肿大淋巴结的形态及内部回声、纵横比（L/T）、彩色多谱勒血流显像（CD FI）及阻力指数（RI）的频谱特征。

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And the other thing is that I can't echo enough the importance of really good hygiene.

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Redford said in the documentary that he didn't expect the echo of "All the President's Men" to remain for so long.

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It's not as if our decisions won't have repercussions that echo down the decades.

WSJ: Peggy Noonan: A 'Necessary' War?