study的过去式和过去分词分别是什么

She studied chemistry for three years.

她学了三年化学。

I studied English and Drama at college.

我在大学学的.是英语和戏剧。

My brother studied at the Royal College of Art.

我哥哥曾就学于皇家美术学院。

The report found that 30% of the firms studied had failed within a year.

据报告称，受调查的公司有30%一年内倒闭了。

He studied politics and economics at Yale.

他曾在耶鲁大学学习政治学和经济学。