Trigger Conditions with 一旦...就
Use 一旦...就 for policies, risks, and actions that start after a trigger.
Pattern
一旦 + trigger, 就 + immediate consequence
Show that one event activates the next consequence.
一旦发现风险，就要采取措施。
When to use Trigger Conditions with 一旦...就
一旦 introduces the moment or condition that activates a result. 就 makes the follow-up feel direct and expected.
一旦决定目标，就不要轻易放弃。
Once you decide on a goal, do not give up easily.
一旦系统出现问题，我们就会通知用户。
Once the system has a problem, we will notify users.
一旦养成习惯，学习会轻松很多。
Once a habit is formed, studying becomes much easier.
一旦机会来了，就要抓住。
Once an opportunity comes, you need to seize it.
Common traps
- 一旦 is stronger than 如果 because it imagines the trigger actually happening.
- Use 就 to connect the immediate consequence.
- Avoid using 一旦 for a condition that is vague or unrelated to the result.
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