题目

已知集合A={y|y=log2x,x＞1},B={y|y=(12)x,0＜x＜1}，则A∩B为(    )A.(0,)                 B.(,+∞)               C.(,1)             D.(0,2) 答案：解析：A={y|y=log2x,x＞1}={y|y＞0},B={y|y=()x,0＜x＜1}={y|＜y＜1}，则A∩B={y|＜y＜1}，故选C.答案：C已知等差数列{an}的前n项和为Sn，且a3+3a6+a9=15，则S11等于A.78B.66C.55D.33