Question

There is a u student in the classroom（改为复数句）

Answer 1

There are some students in the classroom.
因为there没有复数，所以照抄
is的复数是are
然后，a的复数是some
student的复数是students
in the classroom都没有复数，照抄。
所以答案是There are some students in the classroom.

Answer 2

There are some students in the classroom

Answer 3

1楼正确！