要是⋯⋯，（就）⋯⋯，否则⋯⋯
Explanation
该结构用于表达假设条件及其可能引发的两种结果，前半句提出假设情况，后半句用'否则'引出未满足条件时的负面后果。
This structure expresses hypothetical conditions and their potential outcomes. The first clause presents a condition, while 'otherwise' introduces negative consequences if the condition is not met.
Examples
要是他不去，我也不去了，否则我一个人去太危险了。
If he doesn't go, I won't go either. Otherwise, it would be too dangerous for me to go alone.
要是明天下雨，我们就不去爬山了，否则会冻感冒的。
If it rains tomorrow, we won't go hiking. Otherwise, we might catch a cold from the cold weather.
要是你不带包，我就带一个，否则买的东西没地方放。
If you don't bring a bag, I'll bring one. Otherwise, there would be nowhere to put the things we buy.
Related Grammar Points
一旦⋯⋯，就⋯⋯HSK 5五46
句子的类型 · 假设复句
“一旦……就……”是表示条件关系的关联词结构，用于表达某种条件一旦发生，就会立即产生相应的结果。“一旦”引出假设的条件，“就”强调结果的即时性和必然性，常用于假设复句。
The structure '一旦……就……' is a conditional connector used to express that once a certain condition is met, a corresponding result will immediately follow. '一旦' introduces the hypothetical condition, while '就' emphasizes the immediacy and inevitability of the result, commonly used in hypothetical complex sentences.
Examples (3)
一旦考试不及格，我就要延期毕业了。
If I fail the exam, I will have to postpone my graduation.
一旦地铁建成，堵车的情况就可大大缓解。
Once the subway is completed, traffic congestion will be greatly alleviated.
中文一旦学起来，就再也放不下了。
Once you start learning Chinese, you can never put it down.