已知命题P:∀x∈R,ax2+2x+3>0.如果命题¬P是真命题,那么a的范围是 发布时间:2017-04-14 11:28 │ 来源:www.tikuol.com 题型:选择题 问题: 已知命题P:∀x∈R,ax2+2x+3>0.如果命题¬P是真命题,那么a的范围是( )A.a<13B.0<a≤13C.a≤13D.a≥13
题型:选择题 The famous director Li’an failed many times but he eventually _____ to achieve success.A.broke upB.broke offC.broke throughD.broke away 查看答案
题型:选择题 I think grammar is a great way learn a language.[ ]A. study, for B. learns, of C. studying, to 查看答案