Can conference papers use the original words in published papers? Conference papers are often only about 10 pages. When I was writing conference papers, some words seemed unnatural. Can I directly use the original words in someone else's paper? Not a conclusion or opinion. For example:

In this paper, we investigate and present a new type of hardware vulnerability to covert timing channels exposed by [Other people's methods]

I changed it to mine in the thesis:

In this paper, we investigate and present a new type of hardware vulnerability to covert timing channels exposed by others + [my method]

Is this feasible? I just used its sentences to express my idea
I think you can. Some sentences will inevitably be the same in multiple papers. This is, in my eyes, not necessarily plagiarism. Plagiarism is taking &quot;someone else's work or ideas and passing them off as one's own&quot;. What you are doing here is taking somebody else's words that describe work or ideas and passing them off as your own.
That said, in a case like this there is absolutely no reason why you shouldn't just change the sentence to avoid any perception of plagiarism. For example:

Past methods have exposed a new type of hardware vulnerability to covert timing channels [REFs]. Using 'my method' we investigated such vulnerabilities and present them in this work.