以下是朗文Advanced Part5的兩道問題，希望高手不吝賜教
TRANSITION WORDS
3. The ads can bring in revenue;___,because they are government
sponsored,they can keep our costs to a minimum.
(A)for example (C)moreover
想問:答案(C)moreover，但是用(A)for example
這廣告帶來收益，舉例來說，因為政府的補助，所以他們花費最少.
用for example來表示為什麼有收益，並舉例理由，這種文法不行嗎？
COORDINATE CONJUNCTIONS
10Lee took the brochures to the printer's last Friday,
___Tina picked them up early this morning.
(A)and (C)so
想問:答案(C)so，但是用(A)and
李上禮拜五拿手冊去列印，所以Tina今天早上將它們給拿回來.
這樣文意好像也沒有問題，為什麼不能用SO？