题目

The hotel is across ________ the post office, 8 hundred meters away ______ our school.A. between, from B. behind, to C. from, from D. to, of 答案：C 如果a，b，c满足a2+2b2+2c2-2ab-2bc-6c+9=0，则abc等于(    ) A.9          B.27          C.54          D.81