____to master the books,the owner started out seriously.这里填determining还是being determined?

你好.是determined.------表“原因”.
== As / since he was determined- - - - - - .
下面的例句可以简化你的理
As she was tired, she went home earlier to have a rest
== Tired, she went home earlier to have a rest

determined 与 tired 的语法功能一样.