根据《中华人民共和国消防法》的规定，住宅区的物业服务企业应当对管理区域内的()进行维

（8分）甲同学为了区别氢氧化钠和氢氧化钙溶液，设计了如下图所示的四组实验方案。

（1）其中能达到实验目的的是________________

（2）在C组实验中发生的化学方程式为________________________________

（3）实验结束后，甲同学将A、C组四支试管中的溶液倒入同一容器中，看到溶液变浑浊，该现象说明有________________物质生成（填化学式），滴入酚酞后溶液呈红色。

（4）滴入酚酞后溶液呈红色，说明溶液呈碱性。使溶液呈碱性的物质是什么呢？甲同学进一步推测：溶液中呈碱性的物质可能是碳酸钠、氢氧化钙和________________三种物质中的一种，或是三种物质两两混合组成的混合物。

（5）为了验证推测，甲同学查阅资料，获悉氯化钡溶液呈中性，并设计如下实验加以验证。请根据要求完成下列空白：

实验内容	预测现象	结论
取少量容器中的上层溶液于试管中，加入过量的氯化钡溶液，静置	①若有白色沉淀，溶液呈无色	物质是碳酸钠
	②若无沉淀生成，溶液呈红色	物质是氢氧化钙
	③若有白色沉淀，溶液呈红色	____________________

（6）乙同学认为甲同学第②部验证的结论不严密，原因是________________；________________。

Ask yourself whether you have a balance between work and play. Too much of one creates a

sacrifice or loss with _____.[ ]

A. another

B. the other

C. the others

D. others

"What does the middleman do but add to the price of goods in the shops " Such remarks are aimed at the intermediate operations between manufacturers and final customers. This practice usually attracts a lot of attention from the public and the press and the operation most talked about is what is often called wholesaling.
The wholesaler buys goods in large quantities from the manufacturers and sells them in smaller parcels to retailers, and for this service his selling price to the retailer is raised several percent higher. But his job is made more difficult by retail demand not necessarily running level with manufacturers’ production. Because he adjusts or regulates the flow of goods by holding stock Until required, he frees the manufacturer, to some extent, from the effect on production of changing demand and having to bear the whole risk.
The manufacturer can then keep up a steady production flow, and the retailer has no need to hold heavy stocks, who can call on the wholesaler for supplies any time. This wholesale function is like that of a valve in a water pipe. The middleman also bears part of the risk that would otherwise fall on the manufacturer and also the retailer.
The wholesaler provides a purely commercial service, for which he is too well rewarded. But the point that is missed by many people is that the wholesaler is not just someone adding to the cost of goods. It is true one could eliminate the wholesaler but one would still be left with his function: that of making sure that goods find their way to the people who want them.

"Middleman" in the passage almost equals to all the following in meaning EXCEPT ______.

A．go-between

B．intermediary

C．manufacturer

D．wholesaler

下列各项中，属于"问题解决"的是（）。

A.穿衣服

B.回忆朋友的名字

C.完成口头作文

D.浮现童年的生活情境

建立完善的万能钥匙使用和保管，制度，防误闭锁装置不能随意（），停用防误闭锁装置时，要经本单位（）批准。