Indirect questions (embedded questions) are considered one of the challenging grammar points for many ESL/EFL students. One of the issues for students is the difference between the complementizers whether and if which have been discussed by researchers from different perspectives. Students also find it difficult to distinguish the conditional if and the interrogative if. Another fact which makes this grammar point for the students problematic is how indirect questions are used in spoken and written language in terms of word order. Students also sometimes find it hard to distinguish nominal relative clauses and subordinate open interrogatives semantically and syntactically. This paper addresses the most important aspects of indirect questions, most of which are not discussed in course books.
