Miss Sullivan clarified the science Project in Simple but vivid language so as to make it easier for teenagers .
A. understanding
B. to understand
C. understood
D. to be understood
网友回答
A. understanding
(答案→)B. to understand
C. understood
D. to be understood
解析：句意：苏利文小姐用简单但是生动的语言解释科学项目，为了让年轻人理解起来容易。这里使用了句型：make it+adj. for sb to do，it是形式宾语，不定式是真正的宾语，所以选B。