等差数列{an}的前n项和为Sn,若a2=1,a3=3,则S4=______. 发布时间:2017-04-28 18:55 │ 来源:www.tikuol.com 题型:填空题 问题: 等差数列{an}的前n项和为Sn,若a2=1,a3=3,则S4=______.
题型:填空题 Read and write. (看字母写出单词)1. e, e, m, r, t 2. o, t, n 3. a, c, e, h 4. v, e, e, n 5. i, e, z, s 6. e, a, w, r 查看答案
题型:填空题 Look! Li Lei and Ling Feng ___ kites over there. [ ]A. is flying B. are flying C. fly D. flew 查看答案
题型:填空题 患者男,30岁。30分钟前被刀刺右前胸部,咳血痰,呼吸困难。体检:血压107/78mmHg,脉搏96次/分,右前胸有轻度皮下气肿,右锁骨中线第4肋间可见3cm长创口,随呼吸有气体进出伤口响声。此时应采取的急救措施是()A.吸氧B.静脉穿刺输液C.摄胸部X线片D.立即闭合胸部创口E.立即剖胸探查 查看答案