人耳可听到的声音频率范围是()A.1~20Hz B.5~20Hz C.5Hz~5kH 发布时间:2017-07-19 04:57 │ 来源:www.tikuol.com 题型:单项选择题 问题: 人耳可听到的声音频率范围是()A.1~20HzB.5~20HzC.5Hz~5kHzD.16Hz~20kHzE.20kHz以上
题型:单项选择题 With Father's Day around the corner, I have taken some money out of the bank _____ presents for my dad.A. buyB. to buy C. buying D. to have bought 查看答案
题型:单项选择题 净现值是反映投资方案在计算期内获利能力的动态指标,净现值也是评价项目盈利能力的绝对指标,当方案的()时,说明该方案能满足基准收益率要求的盈利水平,故在经济上是可行的。A.NPV>0B.NPV≥0C.NPV<0D.NPV≤0 查看答案