study的过去式是studied。以下是“study”的过去式“studied”的例子：

　　I studied for three hours last night before the exam.

　　(昨晚我为了考试学习了三个小时。)

　　They studied the report carefully before making a decision.

　　(他们在做出决定之前仔细研究了报告。)

　　We studied together in the library every day last semester.

　　(上个学期我们每天一起在图书馆学习。)

　　He studied abroad for two years and learned a lot.

　　(他在国外学习了两年，学到了很多。)

　　She studied hard for the piano exam and passed with flying colors.

　　(她为钢琴考试努力学习，最终取得了优异的成绩。)

　　在这些例子中，“studied”是动词“study”的过去式，用于描述过去发生的学习行为或状态。