The need to communicate is a key characteristic of human society.
需要交流是人类社会最重要的`一个特征。
Cost was a key element in our decision.
价钱是我们决策时考虑的主要因素。
Good communication is key to our success.
良好的沟通是我们成功的关键。
These units played a key functional role in the military operation.
这些单位在军事行动中起到了主要的职能作用。
The president appears likely to change course on some key issues.
总统看起来可能要在某些重要问题上改变方针。