固定成語，表示「等真正遇到問題再處理」。one 較書面，日常口語多用 I/we/you 等主詞；that bridge 為固定說法；when we come/get to it 皆可，但 come 較典型。常見句型為 We'll/I'll cross that bridge when (主詞) come(s) to it。
合併形式範例：
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A: What if our science fair project fails? B: We'll cross that bridge when we come to it.
A：如果我們的科展失敗怎麼辦？B：到時候再說。
其他形式：
cross that bridge when we come to it
最常見、最自然的口語版本，多用未來式主句 + when 子句現在式。
cross that bridge when I come to it
主語改為 I，表達個人將來遇到情況再處理。
cross that bridge when we get to it
以 get 取代 come，口語常見，語意相同。
常見錯誤
✗
We'll cross the bridge when it comes.
✓
We'll cross that bridge when we come to it.
成語為固定搭配 that bridge；且是「我們走到那座橋（問題）再說」，不是「它（問題）自己過來」。句型主語與動詞方向不可顛倒。
✗
We'll cross that bridge when we will come to it.
✓
We'll cross that bridge when we come to it.
英文時間副詞子句（when 等）表未來時，用現在簡單式，不可再用 will。
✗
We'll cross over that bridge when we come to it.
✓
We'll cross that bridge when we come to it.
cross over 可用於「真的過橋」的字面意思，但此為慣用語，固定說法是 cross that bridge，不加 over。