study的过去式和过去分词？

study 双语例句

例句 1. Reading for pleasure and reading for study are not the same.

读书以自娱和读书以学习是不相同的'。

例句 2. We will study the report carefully before making a decision.

我们将认真研究这份报告，然后再作决定。

例句 3. They studied the geographical distribution of the disease.

他们研究了这种疾病的地域分布情况。