I found it no use _______ to persuade him to give up smoking. A. Try B. to try C. trying D. having t

I found it no use _______ to persuade him to give up smoking.
A. Try B. to try C. trying D. having tried
【答案】C
【解析】
【详解】考查动名词及其固定用法。句意：我发现劝他戒烟是没有用的。find it no use doing sth为固定用法，表示“发现做某事没用/只是白费力气”，由此可以排除A和B；这里it做形式宾语，真正的宾语是trying to persuade him to give up smoking这件事情。题目并没有强调try这个动作和主句动作find之间的先后顺序，所以不需要用完成时态，排除D项。故选C项。