We have fallen behind.

我们已经落后了。

youdao

I have fallen behind in my work since last week.

从上周起，我在工作中落后了。

youdao

Some students even play the CARDS in class so that they have fallen behind in their study.

一些学生甚至在课堂上玩这些卡片，以致学习成绩下降。

youdao

Many of these borrowers have fallen behind on their loan payments or defaulted over the past few years.

WSJ: Toxic? Says Who? Taste

"We must have high expectations for children who are more difficult to teach or who have fallen behind, " Bush said.

CNN: Bush calls education 'civil rights issue of our time'

To illustrate how times have changed, one only has to look at how far Wales have fallen behind their greatest rivals England.

BBC: The state of the Union