函授

例句：

1. 1. I've decided to enroll in a correspondence course to improve my English skills.
   我决定报名参加一个函授课程来提高我的英语技能。
2. 2. The school offers a variety of correspondence courses for students who are unable to attend classes oncampus.
   学校为无法在校上课的学生提供各种函授课程。
3. 3. Many people choose to take correspondence courses as an alternative to traditional classroom learning.
   许多人选择通过函授课程作为传统课堂学习的替代方式。