人物话题词汇 — 英语填空题

根据句意和所给汉语提示，用本单元所学词汇的正确形式填空。Tu Youyou ___（坚持）on using lower heating temperatures to extract artemisinin, which proved to be a ___（关键的）step in the research. Her team's ___（目标）was clear, and every member was ___（承诺，献身）to the work despite many difficulties.