题目

--Did Jack come back early last night? --Yes, it was not yet eight o'clock ______________ he arrived home. A. before          B. when       C. that        D. until   答案：B把函数f(x)=sin(x-π3)图象上每一点的横坐标缩小为原来的13（纵坐标不变），再把所得的图象向左平移π9个单位，所得图象的解析式为：______．