challenge的词根词源为chal
例句
1.
Schools must meet the challenge of new technology.
学校必须迎接新技术的挑战。
2.
The company faces major challenges over the course of the next few years.
这家公司今后几年将面临重大的挑战。
3.
It was a direct challenge to the president's authority.
这是对主席权威的直接质疑。