单选题＿＿＿＿＿＿＿＿ in line for half an hour, Tom suddenly realized that he had left his wallet at home. 的答案

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题目内容：
＿＿＿＿＿＿＿＿ in line for half an hour, Tom suddenly realized that he had left his wallet at home.
题目选项

To have waited

Having waited