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一来……，二来……，三来……：Presenting Three Reasons
一来……，二来……，三来…… organizes three supporting reasons or considerations in a clear sequence. Learn to use it in explanations, recommendations, and questions without treating the sequence as proof that the reasons differ in importance.
这个方案值得继续推进：一来市场需求稳定，二来团队已经积累了相关经验，三来前期投入可以逐步收回。
Read the full explanation and examples
Meaning and use
一来……，二来……，三来…… introduces reasons or considerations in sequence: first, second, and third. The parts normally support one overall statement, proposal, or answer. It is useful when a speaker wants to make several grounds easy to follow in conversation, discussion, or more formal explanation.
The numbering makes the organization explicit, but does not itself rank the reasons. The reasons may be distinct, complementary or related. This lesson practices three reasons with 三来. The shorter 一来……，二来…… is also a normal, complete way to give two reasons, in speech or writing; it is not an unfinished three-part list unless the speaker has promised three points.
Form and sentence shape
Each numbered marker is followed by a reason clause or phrase. The three reasons should answer the same implicit question and fit the same overall claim. They need not have identical grammar, but balanced phrasing makes the sequence easier to understand. A colon before the series is a common way to introduce it in writing; it is not part of the spoken pattern.
The numbered reasons can follow a statement or answer a preceding question. In the question-and-answer example, the first sentence asks why, and a separate response supplies the reasons. 一来……二来……三来…… does not itself turn a statement into a question, nor does it require a particular tense or special verb ending.
Examples in context
Notice how each example keeps one topic and adds three connected reasons. The first two explain a plan or decision; the question example asks for reasons and then gives them.
这个方案值得继续推进：一来市场需求稳定，二来团队已经积累了相关经验，三来前期投入可以逐步收回。
她选择留在成都：一来离家近，二来生活节奏适合她，三来当地有她想加入的研究机构。
我们暂时不扩大调查范围：一来样本数量还不够，二来现有数据尚未经过交叉验证，三来团队需要先明确评估标准。
会议改到线上举行：一来几位同事在外地，二来材料需要临时补充，三来线上讨论更方便记录各方意见。
你为什么建议先延期？一来资料还没有整理完，二来合作方尚未确认时间，三来现在仓促决定可能影响后续安排。
这次调整有三方面的考虑：一来减少重复工作，二来让责任分配更清楚，三来为后续协作留出空间。
Useful contrasts and learner checks
The markers number the reasons, not the actions or choices being compared. Use the pattern when all three clauses support one point. If the clauses instead list unrelated events, the numbered presentation can sound forced because the reader cannot see a shared conclusion.
A sentence does not become unsuitable merely because its reasons appear in a different order. The pattern organizes presentation; it does not establish a mandatory ranking. For a coherent explanation, make the relationship between each reason and the main claim clear, and avoid adding a third point that does not support that claim.
他愿意承担这项工作：一来熟悉业务，二来有协调经验，三来时间也安排得开。
- Before speaking or writing, state the position the reasons will support.
- Check that each numbered part gives a genuine reason or consideration for that position.
- Use three parts when practicing the full pattern; keep them focused on the same issue.
- Use a question mark for the question, then let the numbered series provide its explanation.
Scope of this lesson
This lesson covers only the outline item 一来……，二来……，三来…… under parallel compound sentences. The supplied outline establishes this lesson's scope and level; it does not establish which examination version is currently administered at every test centre.
Frequently asked questions
Must the reasons be ranked from most to least important?
No. 一来、二来、三来 marks the order in which reasons are presented. Importance is not specified by the markers themselves.
Can the pattern appear after a question?
Yes. A question can ask for the explanation, and the three numbered reasons can then answer it.
Should I include all three parts?
Use all three when you intend to give three reasons or practice this exact outline pattern. If you have only two reasons, 一来……，二来…… is a complete, normal alternative in both speech and writing.
