painstaking

painstaking
/ˈpeɪnzteɪkɪŋ; `penzˌtekɪŋ/ adj
done with, requiring or taking great care or trouble 极小心的; 辛勤的; 辛苦的
    a painstaking job, investigation 艰苦的工作、 调查
    painstaking accuracy 高度的精确性
    a painstaking student, worker, etc 勤奋的学生、 工人等.

牛津英汉双解词典