to raise difficult questions

From (Duchamp) fixes at stools getting up bicycle wheel then on, vanguard begin frequent to raise difficult questions to the theoretician right away by artist.

自杜尚把自行车轮固定在一把凳子上起，先锋艺术家们就开始频频向理论家发难。

But Zonana said the ruling and other similar cases before the Supreme Court have served to raise further difficult questions: Does someone need to understand death to be executed?

但是Zonana表示最高法院面前的这项裁决和其他类似案件为我们提出了更为艰涩的问题：死刑犯需要理解被处死吗？

Fourth, should train students' problem consciousness, teach the method to raise doubts and difficult questions for discussion.

第四，要培养学生的问题意识，教给质疑问难的方法。