challenge的形容词词

It is not just readers who are challenging the media elite.

挑战媒体精英的不仅仅是读者。

Once upon a time the physical book was a challenging thing.

从前，实体书是一件具有挑战性的`东西。

Killy began challenging the basic theories of racing technique.

基利开始挑战赛车技术的基本理论。