已知椭圆(a>b>0)的左右焦点分别为F1,F2.P是椭圆上一点.PF1F2为以F2P为底边 的等腰三角形,当60°<PF1F2<120°,则该椭圆的离心率的取值范围是( )
我是小小数学家,动脑筋算一算。(18分)
根据问句选择相应的答语,有一答案多余。(12分) ⑴Good morning!( ) ⑵Who's that boy?( ) ⑶Happy birthday!( ) ⑷Nice to meet you.( ) ⑸Who's that woman?( ) ⑹How are you?( )
E.Nice to meet you,too. F.Thank you. G.I'm ten.
老师在班会上让你介绍一下你的家人时会说:________ A.Look at your family. B.Show me your vest. C.Introduce your family.
你想告诉医生你的年龄,可以说:________ A.I'm fine. B.I'm eleven.C.How old are you?
你想知道盒子里装的是什么,你会问:________ A.Who's that? B.Who's this?C.What's in the box?