在写论文时，你应该列出几个关键词来帮助读者快速理解主题。

When writing a paper, you should list a few ___keywords to help readers quickly understand the topic.

在写论文时，你需要确定几个关键词来概括你的研究主题。

When writing a paper, you need to identify several ___keywords to summarize your research topic.

在Java中，'class'和'void'是定义程序结构的关键字。

In Java, 'class' and 'void' are ___keywords used to define program structures.