a. 有计划的, 慎重的
adj. 有计划的；故意的v. 学习（study的过去式）
原型:study 过去式:studied 过去分词:studied
1、Has he studied French very long 他学法语已经很久了吗
2、he studied very hard 他学习很努力
3、scientists have studied 科学家研究
4、studied hard at 努力学习于
5、studied hard for exam 为了考试而努力学习
6、studied hard online 努力在线学习
7、studied harder 更努力的学习
8、studied hardly 努力学习
9、she studied very hard 她学习很努力
10、was studying studied 正在研究
11、the most thoroughly studied 最彻底的研究
12、have studied 学习了（study的现在完成时形式）
13、studied in 在（某一领域）学习在（某地）学习
14、studied hard 努力学习
15、poorly studied 学习不好
16、experimentally studied 实验研究