Is it permissible for a teacher to hint at or explicitly reveal exam questions to students?

It is not permissible for a teacher to explicitly or implicitly reveal examination questions, as this constitutes forbidden deception. The purpose of an examination is to ascertain the students' level and their comprehension, and their results reflect the teacher's effort. Therefore, it is not permissible for him to improve results by providing the questions, as disclosing them is a betrayal of trust.