核心问题
The very successes of physics and chemistry have ensured that biology should now present the key problems of the whole of natural science, offering a challenge to the understanding of the world in which we live...
[原译]物理学和化学的种种成就已经保证了生物学现在应该提出一些为了了解我们生活所在的世界就不能不加以解决的、整个自然科学的关键问题……(《英汉比较语法
纲要》，p.167）
词典解答
见 challenge。