you should say: 你应该说 talk about a subject you would like to in the future. 谈论一个主题,你想研究未来 What you need to study as part of that subject: 你需要研究,对这一议题的一部分 这几句话主要就是要你谈论你的未来,针对这部分来研究看看
What you need to study as part of that subject 这句话完整的句型应该是: what you need to study (what 从句作主语)+as part of that subject (介词短语从后置定语)+ is...... 翻译应该是:(从事)那一学科,一方面你需要学习的是。。。。。