came / had never learned / found / felt / wasn't / was / is written / aren't / is / knew / was / worked / spent / practised / did/ liked / wasn't thought was
纵观全文,练习了一般过去时这一语法,都是在陈述过去的事实.（除去Had never learned,这个动作发生在came 之前；中间这几个 is written / aren't / is 是客观事实,所以用了现在时 ）