To be inconstant or wavering in one's loyalty, principles, or commitment; to be fickle.
他在工作中总是二三其节，对不同的项目一会儿热情，一会儿又失去兴趣，让人很难把握他的真实想法。
He is always fickle in his work, showing enthusiasm for different projects one moment and then losing interest the next, making it difficult to grasp his true intentions.
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