for + 一段時間

... She _____ that every day for one month. Finally, Ted understood ...
(A) did .... (C) has done

釋疑 第17題
http://cap.ntnu.edu.tw/exam/9101/9101reply-e.pdf

對照題目內容(短文)看較完整
http://cap.ntnu.edu.tw/exam/9101/9101e.pdf