Quote, paraphrase, or don’t use「引用」与「换句话说」
What are quotations and paraphrases and why do writers employ them? The question is a good one. Some writers clearly haven't figured it out. A person is quoted or paraphrased because the person speaking is a relevant, authoritative voice. A quote is used because it is weighty or memorable. Paraphrasing occurs either as a succinct summary of something relevant, or because the paraphrase contains a key word or phrase, which is bracketed in quote marks for emphasis.
Always clearly attribute paraphrased or quoted material to its author, such as, “According to city historian Lee Chen,…” Attribution should be near the borrowed material to avoid confusion. Quotations should be exact and in proper context, whereas paraphrases obviously should not be word for word, but must be accurate in thrust and tone. And beware of writing sentences that duplicate a source's original structure; it is possible to plagiarize the construction of content.
You say, if quoting a source is fraught with so many dangers, why should I do it? You shouldn't, unless a paper will be weaker without attributed material. But it also is true that a paper will be weak if it contains too much borrowed material, even when attributed, so use only as much as necessary to document a point. Research uncovers worthy ideas and statements. Using them to buttress an argument in a paper is perfectly justified—so long as you don't try to steal them.