讲清楚

• spell out
• make clear

例句

1. 这位讲师虽然对自己的学科很熟悉，却无法把有用的东西向学生讲清楚。
   The lecturer, though he knew his subject inside out, was quite incapable of getting anything useful over to the students.
2. 把道理跟你母亲讲清楚，她肯定会想得通的。
   Reason things out with your mother; she sure will come round.