问题
选择题
________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
答案：C
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.