为什么要用been呢?

母语人士的回答
Rebecca
在这里, been是一种表示过去发生的可能性的装置。换句话说, Could have been只是添加了动词to be could have示例: That could have been the first time I saw a shark! (也许那是我第一次看到鲨鱼!) 示例: You could have been first but instead you got last place. (你可能是第一名,但最终你却是最后一名。)