【题目】---Did you have any trouble catching the professor’s lecture?
---No. He spoke very slowly and clearly to make it easy _____.
A. to understandB. understand
C. understandingD. understood
在线课程【答案】A
【解析】
考查固定结构。句意：——你听教授的课有困难么？——不，他讲得很慢且清楚以便让人很容易理解。此处为形容词+不定式作宾语补足语，表示“做某事是……的”，故A项正确。