始祖鸟的大小和乌鸦差不多,图为始祖鸟化石,从化石分析,始祖鸟的身体被覆____;具有和鸟翅膀一样的____,但前肢的末端有指,指的末端有____;它的嘴里有____,嘴的外形像____,尾长并有尾椎骨.也就是说,始祖鸟的身体结构既和____有相似之处,又和____有相似之处.
The two cities have reached an _________ to develop science and technology.
①S1+S2=S3+S4;②S2+S4=S1+S3;③若S3=2S1,则S4=2S2;④若S1=S2,则P点在矩形的对角线上.
其中正确的结论的序号是____(把所有正确结论的序号都填在横线上).
(____) 1. Is Danny tall? A.He's Peter.
(____) 2. Hello, Dolly. This is Mr Wang. B.Yes, he is.
(____) 3. How old are you, Ben? C.Hello, Mr Wang.
(____) 4. Good afternoon, boys and girls. D.I'm eight.
(____) 5. Who's your friend? E.Good afternoon, Mr Zhang.
实验步骤:
①先连接如图所示的装置,检查好气密性,再加入试剂;
②加热A试管,待B试管中品红溶液退色后,熄灭酒精灯;
③将Cu丝向上抽动离开液面.
请回答下列问题: