MARK!

非常tricky！！！！ 有former都不对，不能做18年的前主席

语义语义语义！！！！！
前主席”是他现在的身份 “主席”是他原来的身份
他是做了18年的“主席” 而不是做了18年的“前主席”
而且他“参加会议”是他原来做的事情

she was the chair for 18 years.

NOW she is the former chair.

she will retain the title 'former chair' in perpetuity, since it is impossible for someone to stop being 'the former _____'. thus it is nonsense to attach a finite duration (18 years) to 'the former _____'.

过去的时点就没必要用former了。。。

Luci, you are missing a nuance in the meaning of the sentence that is difficult even for a native speaker of English to identify. An individual would not be the former chair of a planning board for 18 consecutive years; instead, the sentence is attempting to say that Joan was actully the chair of the planning board for 18 consecutive years and that she attended these meetings during those 18 years. Thus, choices A, B, and C and be eliminated. As D is a run on sentence, E is the best answer.

"Former" is exactly like "ex-", so maybe that will help you understand.
Let's say some male executive, Harold, was married to a woman named Sherry, but they've divorced. In this case, you can probably understand why this sentence is nonsense:
As Harold's ex-wife, Sherry entertained many of his clients in their country home.
Clearly it should say "As Harold's wife". (Unless these two were very weirdly close after their divorce.)

former chair 也可以连续18年啊，为什么就冲突了？而且因为句子中没有对比时间点，所以用 attended 过去式没问题吧