present perfect tense

你好，其实看你想问怎样的问题，可是我觉得你会问 Are you interested in joining the event? 的可能性比较高一点咯，因为它的意思是说“你有兴趣参加那个(比赛)项目吗？”咯。

如果你想用 Present Perfect Tense 的话，也是可以的，那句子就会写成 Have you been interested in joining the event? 咯，我们是需要加 been 在 interested 的前面，因为在这里的 interested 是个形容词 (adjective)，而不是动词 (verb) 来的。

Present Perfect Tense 的结构是 has / have + past participle of verb，由于我们在形容词的前面需要放一个系动词 (linking verb)，例如 be (is, are, was, were etc.)，所以变成 has / have + been 咯。

希望能帮到你咯。。。: )

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The original one is in present tense, should read:
Are you interested in joining the event?

In present perfect tense:
Have you been interested in joining the event?