评价他人演讲的优缺点时，可以使用以下英文句子：

Your speech is great, but it still lacks self-confidence.

你的演讲很棒，但还是缺乏自信。

You sound good, but not enough solid basic skills.

你的声音不错，但是基本功不够扎实。

Your language is very fluent, but your speech lacks a deep understanding of the content.

你的语言很流畅，但对于演讲内容的理解还不够深刻。

The speaker's delivery was engaging and confident, effectively capturing the audience's attention.

演讲者的表达引人入胜且自信，有效地吸引了观众的注意力。

Their tone was clear and articulate, making complex ideas easily understandable.

他们的语气清晰且富有表现力，使复杂的概念易于理解。

It's terrific to see you dress formally and well prepared for the speech, and your poster is well done as well.

很高兴看到你穿着正式且准备充分，演讲海报也做得很好。

However, you need to make more eye contact with the audience.

然而，你需要更多地与观众进行眼神交流。

The points are clearly visible to the audience. You have used bullet points for important information and expand on it while presenting instead of writing a long paragraph and reading it.

观点对观众来说是清晰的。你在展示时使用了项目符号来强调重要信息，并进行了扩展，而不是直接阅读长篇段落。

这些句子可以帮助你全面而具体地评价他人的演讲，既指出优点也提出改进建议。