crucial 至关重要的，决定性的
例：The nineteenth century should be reckoned as the crucial period for the change in the structure of science.
19世纪应该被看做科学结构变化的关键时期。
同义词：important，significant，vital，decisive，conclusive
派生词：crucially 重要地，关键地
真题链接：If we are ever going to protect the atmosphere，it is crucial that those new plants be environmentally sound.
（2005）如果我们准备保护大气，那么关键的就是这些新工厂要对环境无害。
