Definition: something that is difficult and that tests someone's ability or determination Level: B1
解决这个问题对科学家来说是一个巨大的挑战。
Solving this problem is a great ___challenge for scientists.
她准备好迎接挑战了。
She is ready to rise to the ___challenge.
在我们的冒险中，我们面对了许多挑战。
We faced many ___challenges during our adventure.
