Found for conversation and Olofsson (1981) and Biber. Conrad. Conrad. And Reppen (1994)
found for written discourse would be a useful way for ESL/EEL teachers to decide that to
teach about relative clauses and when and how to present the information. Usage tendencies seem to be linked very specifically to given discourse genres, topics. And also to modality (speech vs. writing). Much more research is needed along the lines of the studies reported here we are to establish better informed pedagogical priorities in this area.