Question

he has been studying very hard because he doesn't want to fall___his friends

he has been studying very hard because he doesn't want to fall___his friends

Answer 1

为你解答。
He has been studying very hard because he doesn't want to fall (behind，在后面） his friends.
他一直努力学习，因为他不想落在朋友们的后面。
解释：fall behind，落后。

追问

后面不用加介词的吗？

追答

behind（在后面）就是介词。