简答题I haven't heard from you. You left Shanghai. (since)答案:I haven't heard from you since you left Shanghai.解析:考查时间状语从句。句意:自从你离开上海后,我就没有收到过你的信。根据所给连词since,意为,自从,可连接两个句子。故答案为:I haven't heard from you since you left Shanghai.