Teacher called these students difficult to control.
In this sentence, there is no "to be" between difficult and students, which somehow so strangely led me to thinking that using adjective complement "to control" after adjective "difficult" is wrong. Is it OK to use adjective complement when there is no "to be"?
Another example.
Students were called difficult to control.
So, are those sentences grammatically correct? Thank you so much in advance.