20 Among the parameters that determine whether an environment is suitably for life as we know it are temperature, water availability, and oxygen content.

答案：B

分析：改为suitable，be加形容词

感觉句子的结构很混乱，好多地方都不能理解为什么这样子用

比如，句子的主干是什么？整个句子以among开头，后面嵌套的从句是什么从句？

as we know it are 这个说法也感觉非常怪异，有什么语法依据吗

这句话似乎有语病，改成 Among the parameters that determine whether an environment is suitable for life as we know it, the most important ones are temperature, water availability, and oxygen content. 会好些。as we know 和as we know it意思不一样的。前者意思是众所周知，后者意思是据我们所知。