一般楼梯是由（）组成。A.扶手 B.梯段 C.栏杆 D.平台和中间平台 E.梯段梁

过氧化氢（H₂O₂）是一种无色粘稠液体，其水溶液又俗称双氧水，呈弱酸性，医疗上用作外科消毒剂。研究表明：H₂O₂具有立体结构，两个氢原子像在半展开书本的两页纸上，两页纸面的夹角约为94°，氧原子在书的夹缝上，O－H键与O－O键之间的空间夹角约为97°

⑴H₂O₂的电子式为      ，其分子属于      （填：“极性”或“非极性”）分子。

⑵经测定，H₂O₂为二元弱酸，其酸性比碳酸弱，请写出其第一步的电离方程式_____________。

⑶H₂O₂溶液与一种弱酸的酸性氧化物反应生成强酸，该反应的离子方程式为              ，

并在方程式上标出电子转移的方向与数目。

⑷为了贮存、运输、使用的方便，工业上采用“醇析法”将其转化为固态的过碳酸钠晶体（其化学式为2Na₂CO₃·3H₂O₂），该晶体具有Na₂CO₃和H₂O₂的双重性质。则下列物质能使过碳酸钠较快失效的是（多选）       。

A．MnO₂

B．H₂S

C．稀H₂SO₄

D．NaHCO₃

几种常用药品的通用名与商品名

硝酸异山梨酯

A．泰能
B．泰诺
C．安定
D．消炎痛
E．消心痛

Although your internet start-up company has few project management policies and procedures in place, it made a healthy profit last year. Experience, however, has taught you that some controls are required, especially for projects that change frequently. You would like to establish a change control system for your company, but must convince a group of money-hungry “20 somethings” to use it. To be effective, the change control system must include ______.

A．procedures that define how project documents may be changed

B．specific change requests expected on the project and plan to respond to each one

C．performance reports that forecast project changes

D．a description of the functional and physical characteristics of an item or system

在我国国家机构中居于最高地位的是

A．国家 * *

B．人民政协

C．全国人民代表大会

D．国务院

下列程序段的输出结果是( )。
SET TALK OFF
S=0
I=5
X=11
DO WHILE S＜=X
S=s+i
I=i+1
ENDDO
s
SET TALK ON

A) 5
B) 11
C) 18
D) 26