物业经营管理是以( )物业为对象，为业主提供的贯穿于物业整个寿命周期的综合性管理服

不属于Windows的常用附件是（）。

A.多媒体

B.记事本

C.写字板

D.画图

E.网上邻居

现有某金属硝酸盐化学式为M(NO₃)₂，为了探究其热分解产物,某化学小组开展探究性学习

【查阅资料】金属活泼性不同，其硝酸盐分解产物不同。如

2KNO₃2KNO₂+O₂↑

Cu(NO₃)₂2CuO+2NO₂↑+O₂↑，4AgNO₃4Ag+4NO₂↑+O₂↑

【提出猜想】

猜想1  M(NO₃)₂M(NO₂)₂+O₂↑

猜想2  2M(NO₃)₂2MO+4NO₂↑+O₂↑

猜想3 __________________

【设计实验】为了探究上述猜想，设计如下实验装置

实验步骤：①连接仪器；②检查装置气密性；③取一定量样品装于大试管，并重新连接好仪器；④加热；⑤……

（1）写出猜想3的化学方程式________________；

（2）测定气体体积应选择 ______ （填A或B）；不选另一个装置的理由是__________________________

（3）实验收集到一定量气体，为了检验收集气体的成分，其操作方法是_____________________；

（4）在实验后的水里加入适量碳酸氢钠粉末，溶液中产生大量气体，说明 _______ 正确（填：猜想1、猜想2或猜想3）

（5）该小组测得两组数据：

①实验前样品质量为Wg，收集到气体体积为V L；

②实验前样品质量为Wg，完全分解后测得固体产物质量为m g；

请你选择其中一组数据，计算M的相对原子质量为 _________________  

下列发热疾病中，不伴结膜充血的是（）

A.麻疹

B.流行性出血热

C.结缔组织病

D.斑疹伤寒

E.钩端螺旋体病

The history of African—Americans during the past 400 years is traditionally narrated (1) an ongoing struggle against (2) and indifference on the part of the American mainstream, and a struggle (3) as an upward movement is (4) toward ever more justice and opportunity.

Technology in and of (5) is not at fault; it’s much too simple to say that gunpowder or agricultural machinery or fiber optics (6) been the enemy of an (7) group of people. A certain machine is put (8) work in a certain way—the purpose (9) which it was designed. The people who design the machines are not intent on unleashing chaos; they are usually trying to (10) a task more quickly, cleanly, or cheaply, (11) the imperative of innovation and efficiency that has ruled Western civilization (12) the Renaissance.

Mastery of technology is second only (13) money as the true measure of accomplishment in this country, and it is very likely that by (14) this under-representation in the technological realm, and by not questioning and examining the folkways that have (15) it, blacks are allowing. (16) to be kept out of the mainstream once again. This time, however, they will be (17) from the greatest cash engine of the twenty-first century. Inner-city blacks in particular are in danger, and the beautiful suburbs (18) ring the decay of Hartford, shed the past and learn to exist without contemplating or encountering the tragedy of the inner city.

And blacks must change as well. The ways that (19) their ancestors through captivity and coming to freedom have begun to loose their utility. If blacks (20) to survive as full participants in this society, they have to understand what works now.

19（）

A.servicing

B.encircle

C.encircling

D.served

什么叫“山曲”？有什么特点？