this is why in the early days of radio.有錯誤嗎？怎麽改？

This is because in the earlydays of radio,those who reported the news were expected to speak excellent English.

這是因為在廣播的早期，那些報道新聞的人被要求說壹口流利的英語。

句子分析：

主句主語是this，

系動詞是is,

表語是because引導的表語從句,

in the early days是時間狀語,

of radio作定語修飾前面名詞days.because引導表語從句,

主語是those,

系動詞是were,to speak excellent English是表語.定語從句