可理解的，明白易懂的，明了的，清楚的

• The language of Darwin was intelligible to experts and non-experts alike.

  达尔文的语言无论对专家还是非专业人士而言都明白易懂。

• The answers must be intelligible, but they do not have to be in complete sentences.

  答案必须要清楚明晰，不过不必是完整的句子。