[文法] 想請教研究所的考題

[sazuki (馬克丁小屁孩)]

各位版友好 :


  小弟遇上了些困難，是文法觀念的題目，想破頭都無法有合理解釋>"<

  (1)When I ____ the windows , I sat down and had a cup of coffee.

    (A)had opened (B)have opened (C)open (D)opened



   先將B與C刪去，我以為這是簡單過去式，結果答案卻是A


   為什麼D無法解釋 ???


  (2)Once researchers have obtained information about the chaotic system,

     they can begin to use chaos to their advantage.
                                  ^^^^^

    這裡有困惑的地方是，不瞭解底線部分該如何解釋



 麻煩大家了 >"< !!!!

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◆ From: 140.120.19.4
推 ely6231:http://www.thefreedictionary.com/advantage n. 2.
→ dunchee:看樣子這題出自"Practical English Usage" 參考:
→ dunchee:http://dunchee.blogspot.com/2012/02/temp.html
→ sazuki:謝謝樓上兩位 : )  讓我對時態文法又多瞭解了 !