8. Mary was silent during the early part of the discussion but finally she ____ her opinion on the subject.
A项,give voice to 意为“说出, 表达”;
B项,keep an eye on 意为“留意,密切关注”;
C项,turn a deaf ear to 意为“置若罔闻”;
D项,set foot on 意为“踏上;涉足”。
故正确答案为A。
根据句意,Mary 在讨论的前半部分很沉默,但是最后她针对课题发表了(give voice to)意见。其余各项均不符合文意。
动词词组意思不清致错。