什么是合成标准不确定度？

某外国朋友想考察我国境内最早的人类遗址，他应该去

A．云南元谋

B．浙江河姆渡

C．北京周口店

D．陕西蓝田

Many people are waiting for the train. Some are reading the newspaper and some are saying goodbye to their friends.

Mr. Wang, Mr. Li and Mr. Chen are talking so happily that they don’t know the train is going to leave. The guard says to them, “Hurry up! The train is going to leave.” The three men hear the guard. Two of them jump onto the train quickly before it moves. Mr. Wang is left behind. He looks very sad. The guard says to him, “Don’t feel bad. The next train will come in ten minutes.” “ I know,” Mr. Wang says, “It is my train . My friends only come to say goodbye to me.”

小题1:Mr. Wang ,Mr. Li and Mr. Chen are talking at the station.

小题2:There are only three men at the station.

小题3:Mr. Wang jumps onto the train.

小题4:Mr. Chen and Mr. Li are Mr. Wang’s friends.

小题5:Mr. Chen and Mr. Li really want to jump onto the train.

写出下列反应的化学方程式，并在括号里注明反应的基本类型

（1）用胃舒平（主要成分氢氧化铝）治疗胃酸过多            （       ）反应。

（2）消毒药水（含双氧水）粘到受伤的皮肤上冒泡                    。

（3）铜丝浸入硝酸银溶液中___________________________________ （       ）反应。

（4）用一氧化碳和铁矿石（主要成分Fe₂O₃）在高温条件下炼铁_________________。

引起重症脑炎的主要病毒是（）

A.柯萨奇病毒

B.埃可病毒

C.腺病毒

D.单纯疱疹病毒

E.腮腺炎病毒

在社会主义初级阶段，我国社会的主要矛盾是人民群众日益增长的物质文化需要同落后的社会生产的矛盾。( )