I'm very sorry 后 to do sth.表将要做某事,
to have done 表已经做某事
已经发生的抱歉用,to have done,排除AB
C.to have taken up：占去、占用,
如,I won't take up much of your time.
我不会占用你很多时间.
D.to have wasted:表（粗心、夸张、无目的的）浪费,挥霍 有点夸张,不大礼貌,
选C较合适.
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