"学生都很投入"可以用英语表示为"the students are all very engaged"或"the students are all very invested in their studies"。这个短语源于英语中的动词"engage"和名词"investment"，都表示全神贯注的意思。例句：

The students are all very engaged in their studies, asking thoughtful questions and participating in class discussions.
The students are all very invested in their education, putting in extra time and effort to ensure their success.

中文翻译：

学生们都非常投入学习，提出了有思想的问题，并参与课堂讨论。
学生们都非常投入教育，花费额外的时间和精力来确保他们的成功。