Question

高三英语选择题，答案是C,

______ as a volunteer teacher in Tibet for a year, Linda has become more experienced. A. To work B. Working C. Having worked D. Worked

Answer 1

这里的Having done做原因状语，work 这个动作是become产生的原因。两个动作都是主语Linda发出的。
前面加上主语就是Linda has worked as a volunteer teacher in Tibet for a year.这是使用的是现在完成时，强调过去到现在一段时间的动作发生状态，故常常与一段时间连用，比如后面一般是for和since，这里就有for a year
那么这里只有C选项是现在完成时。

Answer 2

B,C其实都可以，C更合适一些，表示已经完成