An adjective clause is a dependent clause that functions as an adjective which modifies a noun. The aspects of omission and punctuation in the adjective clause have usually caused ambiguities to advanced English learners. The aspect of omission consists of two elements that is the omission of relative pronouns with 'be' and the omission of relative pronouns. The aspect of punctuation also consists of two aspects that is adjective clauses with commas and those without. The objective of this study is to find out in which aspects with their elements of adjective clauses the English Department students have the difficulties; omission, the use of comma in adjective clause, or both of them. The method used in this research was a descriptive qualitative method. The data was collected by using a set of tests. The sample of this research was 20 English Department Students of Syiah Kuala University who have passed Structure IV at least with a B grade. The research results show that the English Department students have difficulty in mastering both elements in the omission aspect and an element which is the adjective clause with comma in the aspect of punctuation. Based on the research results, the writer recommends that the students do more practices on the adjective clause.
I believe that this thesis will be a good reference for Undergraduate and Master's Degree Thesis and Dissertation.