⑴ ____
⑵ ____
⑶ ____
⑷ ____
⑸ ____
A. playing football B. laughing C. crying D. standing E. singing a song
在等比数列{an}（n∈N*）中，若a1=1，a4=18，则该数列的前12项和为（ ）
— ________ it a rabbit?
— No, it isn't.
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