三篇总序，阐明丛书之宗旨，民俗、史诗、长歌与民间文学基本知识，丛书之写作要点。

The three general prefaces state the aims, folklore, epics, long songs and the basic knowledge of folk literature, as well as the main points of the three series.

youdao

最后，序贯行eus - FNA和ERCP理论上是低成本高效率的，它可能缩短总操作时间以及最终组织学诊断报告的时间。

Finally, performing EUS-FNA and ERCP in tandem is presumably cost-effective and may reduce procedure time and the time until the final tissue-based diagnosis is available.

youdao

该装置在总馈电开关处的漏电保护装置使用附加直流电源原理，在分支馈电开关处的漏电保护装置使用零序功率方向式保护原理。

This device use the principle of additional DC power supply in main feeding switch, and use the principle of direction of zero sequence power in branch feeding switch.

youdao