so that; so 問題

1. His sister was too tired of walking.
or His sister was so tired to walk any further.
a. so tired that she can
b. so tired that she can't
c. too tired not to d. so tired to

上面的意見都是極佳的意見。

.. .too .... to (do something)
... too ... not to (do something)

以上兩個句式都有的，但 c 卻有 logical problem，所以不是正確答案。

做這類練習時，除了找出正確答案，亦可以嘗試理解別的答案為何不對。
這類選擇題的不同選擇，很多時錯的答案也是好些人常犯的錯。

不用擔心，可能她只是信心不足．．．

發問者:車厘子:
你可以不相信網上任何人答案, 自己可去查證
但希望你信下列各字典例子

.... too tired to do something
1. “I’m too tired to walk.” ~ Longman Dict.
2. “He was too tired to argue.”~ Oxford A.L.Dict.
3. “She's too tired to go out tonight.” ~ Merriam-Webster Dict.
4. "She was too tired to do any more." ~ Macmillan Dict.

2014-10-14 07:15:03 補充：
tired to do something 不同 tired of doing something

If you are tired of something, you don't want it to continue because you are bored of it or unhappy with it.

tired of doing something = 對做某事,不耐煩或感到厭煩
"tired of ' = 厭倦, 與疲累無關

To yip******
Please look it up in your dictionary. 教錯人不好

2014-10-14 07:39:13 補充：
His sister was so tired that she can’t walk on.

錯原因:
His sister was so tired ~ past tense (過去)
she can’t walk on. ~ present tense (現在)
太累, 是講以前某個時刻狀況
現在狀況如何? 無言及現在太累, 有可能現在不累
兩事件分開地在不同時間, 是無關聯

His sister was so tired that she could not walk on.~ correct