原因

When y＝0.15, the tenability at 10kHz is as high as 35.4% under a relative low electric-field (2.0kV/cm).

当y＝0.15时，在较小的直流偏压下（2.0kV/cm），10kHz下的电场可调度最大可达到35.4％。

In the second part, the author summarizes the development of epics in the period of "middle Tang dynasty" and discusses the deploitation of epic themes .

第二部分主要描述中唐叙事诗的发展盛况，论述其在诗体、题材等方面的开拓与发展。