隧道的主体建筑物是:A.洞门,洞身支护衬砌 B.洞门,洞身,防、排水系统及通风、照 发布时间:2017-07-07 05:29 │ 来源:www.tikuol.com 题型:单项选择题 问题: 隧道的主体建筑物是:A.洞门,洞身支护衬砌 B.洞门,洞身,防、排水系统及通风、照明系统 C.洞门,洞身,通风、照明及安全系统
题型:单项选择题 已知直线l的参数方程是x=1+12ty=32t(t为参数),以原点O为极点,x轴正半轴为极轴建立极坐标系,圆C的极坐标方程为ρ=2cosθ+4sinθ,则直线l被圆C所截得的弦长等于______. 查看答案
题型:单项选择题 In each of the following groups of words, there are four underlined letters or letter combinations marked A, B, C and D. Compare the underlined parts and identify the one that is different from the others in pronunciation. Mark your answer by blackening the corresponding letter on the Answer Sheet.()A. plate B. table C. father D. grape 查看答案