这题对大家来说可能很简单，但我一个文法废实在很疑惑...
题目是“在他到教堂以前，他一直在练习唱歌。”
我的答案是He had been practicing singing before he arrived the church.
参考答案是He had been practiced singing before he started going to the church.
想请教参考答案中的practiced在文法上的解释是？是过去分词做形容词形容been还是？
谢谢啦。

答案错了吧（？

感觉是答案错了

QAQ 难怪我看不懂，谢谢大家