What great trouble the boy his father to give up smoking!
A. had to persuade
B. had persuaded
C. had persuading
D. had persuade
网友回答
A. had to persuade
B. had persuaded
(答案→)C. had persuading
D. had persuade
解析：句意：这个小男孩在说服他的父亲放弃吸烟是多么的困难。这里是短语have trouble in doing做某事有困难；这里省略了介词in；这里是感叹句，被感叹的词是名词trouble所以用what，根据句意故选C。