fall behind sb意思是落在…後面；沒有fall behind with sb這種用法。fall behind with sth，with後面不能接sb，只能接sth，意思是拖欠（付款）；兩者意思不同用法也不同。

1、fall behind sb./sth用法落在…後面例如：She soon fell behind the leaders. 她很快就落在領頭者的後面。If you don't come to class regularly, you will fall behind in your studies. 如果你經常不來上課，學習成績就會落在別人後面。

2、fall behind with sth用法拖欠（付款）；沒有及時做例如：He's fallen behind with his school work again. 他又沒有按時做學校作業。Don't fall behind with the rent, or you'll be evicted. 不要忘記交房租，否則你會被趕出去的！擴充套件資料：behind：英 [bɪˈhaɪnd] 美 [bɪˈhaɪnd] prep.在(或向)…的後面;落後於;支援; adv.在(或向)…的後面;留在原地;拖欠;積壓(工作) n.義同bottom，委婉說法，即屁股例如：He has 20 years of loyal service to Barclays Bank behind him. 他背後有20年忠心為巴克利銀行工作的經歷。固定短語：fall behind with sb 落後於某人；be behind sb 支援；put sth behind sb 拋在腦後；follow close behind sb 緊跟在某人背後。fall behind sb 落在某人後面 ；be right behind sb 支援某人；talk behind sb 揹著人說話；lag behind sb 落後於某人；trail along behind sb 慢吞吞地跟在某人後面走。

沒有fall behind with sb.

應該是: fall behind sb.

拖欠；落在後面

In order to help those students who fall behind other classmates, our teacher Paul is burnt out from weeks of overworking and stress.

為了幫助落後於其他同學的學生，我們的老師保羅因為連續幾周的過度辛勞和壓力而累垮了。