MELDI NOVITA NENOGASU Pengarang YOSEP B. KROON Dosen Pembimbing 1 Soleman Dapa Taka Dosen Pembimbing 2 Fransiskus Bustan Penguji 2 Yosep B. Kroon Ketua Penguji Drs.Soleman Dapa Taka, MA Penguji 1

The aims of this study are (1) to find out the extent level of the mastery of temporal adverbial clauses by the seveneth semester students; (2) to find out what are grammatical difficulties that the students encounter in mastering the temporal adverbial clauses. The researcher took only 40 students in seventh semester of English Study Program. The method used descriptive quantittive and descriptive qualitative method. The focus of this research is the mastery of temporal clauses by recognized the subordinating connector of the sentences. In collecting data, the researcher used test. It consisted of multiple choice. The test consisted of twenty question of multiple choices. Based on the analysis, the researcher conclude that average ability level in mastery the temporal adverbial clauses of the seventh semester student was fair as show by the averages score 60,88 the students has achieved. Detail groupings of the ability of entire group are (a) excellent (15%), (b) good (27,5), (c) fair (17,5), (d) poor (27,5), (e) very poor (12,5). Based on the result, the research suggest that the students should learn more about grammar tha focused on temporal adverbial clauses. Keywords: students’ mastery, temporal adverbial clauses, seventh semester