[单选题]Directions: In this part there is a sentence with four choices marked A, B, C and D. Choose the one that best completes the sentence. I didn't go to his party last night, because（ ）I changed my mind.
A
on a second thought
B
on the second thought
C
on second thought
D
on the second thoughts
正确答案：C
题目解析
本题考查固定搭配的使用。 on second thought是固定搭配意为“经过深思熟虑后”，需要注意的是second前不加冠词，故选C。 句意：我昨晚没去他的派对，因为我在深思熟虑之后改变了想法。
