Definition
to fall behind or become more distant from something or someone
落在后面，掉队，赶不上
If you don’t speed up in the race, you will drop behind.
如果你不在比赛中加快速度，你就会掉队。
As the course progressed, many students found themselves dropping behind.
随着课程的进展，许多学生发现自己落后了。
He failed to keep pace with the project, which ultimately caused him to drop behind overall.
他未能跟上项目的进度，最终导致他整体落后。