看了刘谦的表演,许多孩子都对魔术着了迷.Many children have become interested in

看了刘谦的表演,许多孩子都对魔术着了迷.Many children have become interested in magic since they看了刘谦的表演,许多孩子都对魔术着了迷.Many children have become interested in magic since they watched Liu Qian 's show.答案上是这么写的.为什么是have become 这是什么时态 ..现在完成时不应该是have became 这里是have become