I regret ________ that I'm too busy ________ in the talk．
A.to say; to participateB.saying; participatingC.to say; participatingD.saying; to participate在线课程C
考查非谓语动词。regret to say很遗憾地说；be busy doing忙于做某事。有些动词或词组既可以跟动名词作宾语，也可以跟不定式作宾语，但意义上有区别，要特别注意。