题目

 more visitors, the Beijing Garden Expo Park gives roses to the couples visiting it. A. Attracted                            B. Attracting C. To attract                           D. Having attracted 答案：C。考查不定式作目的状语。句意: 为了吸引更多的游客, 北京花卉博览会公园给来访的夫妇提供玫瑰。空处是作目的状语, 故用动词不定式, 选C。已知函数f（x）=+cosx，则f（x）取得极值时的x值为    ．