题型:解答题 已知数列{an}中,a1=6,an+1=an+1,数列{bn},点(n,bn)在过点A(0,1)的直线l上,若l上有两点B、C,向量BC=(1,2).(1)求数列{an},{bn}的通项公式;(2)设cn=n•2bn,试求数列{cn}的前n项和. 查看答案
题型:单项选择题 男,16岁,下背痛和晨起僵硬1个月,活动后减轻,伴乏力,低热。为进一步明确诊断,以下哪种实验室检查最有价值()A.血清类风湿因子检测B.血清HLA-B27检测C.血冷凝集试验D.血常规E.红细胞沉降率 查看答案
题型:单项选择题 Every device () in the spacecraft must be designed and made with great care so as to be sure that nothing goes wrong in operation.A. to be fittedB. fittedC. fittingD. to have been fitted 查看答案