问题补充:
hard before, Tom is afraid of failing in the exam.
A. Having been worked
B. Not to have worked
C. Having never worked
D. Never have worked
答案:
A. Having been worked
B. Not to have worked
(答案→)C. Having never worked
D. Never have worked
解析:考察非谓语动词.句意:从来没有努力学习过.汤姆担心考试会不及格. 现在分词表示正在进行的伴随性动作,和句子主语是主谓关系. 如果动作发生在谓语动词之前,则要用完成事态的现在分词,结合语境可知选C.