有关施工合同的订立不正确的一项为( )。 A．施工合同作为合同的一种，其订立也要经

（9分）四氧化三铅俗名“铅丹”或“红丹”，由于有氧化性被大量地用于油漆船舶和桥梁钢架防锈，其化学式可写为氧化物2PbO·PbO₂或盐Pb₂PbO₄。欲测定某样品中四氧化三铅含量，进行如下操作：

①称取样品0.1000 g，加还原性酸溶解，得到含Pb^2＋的溶液。

②在加热条件下用过量K₂Cr₂O₇将Pb^2＋沉淀为PbCrO₄，冷却后过滤洗涤沉淀。

③将PbCrO₄沉淀用酸溶液溶解（离子方程式为2PbCrO₄＋2H^＋＝2Pb^2＋＋Cr₂O₇^2－＋H₂O），加入过量KI

溶液，再用Na₂S₂O₃标准溶液滴定到终点（滴定过程中离子方程式为：I₂＋2S₂O₃^2－＝2I^－＋S₄O₆^2－）。

(1)已知Pb的原子序数是82，请写出Pb位于周期表的第_____周期______族。

（2）在PbCrO₄浊液中加入少量酸，则Ksp(PbCrO₄)        （填“增大”、“减小”、“不变”）

（3）写出步骤③中加入过量KI后溶液中发生反应的离子反应方程式               。

（4）欲求试样中Pb₃O₄的质量分数，还需要的数据有                                         。

（5）Fe₃O₄与Pb₃O₄相似，其氧化物和盐的形式分别是                  、                。

The Fifth China International Fair for Investment and Trade is expected to expand the country’s economic relations with the international community when it opens on September 9. The four-day fair will be held in the Economic Zone of Xiamen, a coastal city in East China’s Fujian province. Compared with the previous four fairs held annually since 1997, this year’s fair will provide more detailed information and better services for the participants, according to Xi Jinping, governor of the Fujian province and director of the organizing committee of the fair.

A series of high-level forums will be held on international investment and China’s entry into the World Trade Organization. Since 1997, Xiamen has successfully hosted four sessions of the China International Fair for Investment and Trade, drawing global attention. Xiamen will redouble its efforts to offer better services for all its guests and friends attending the fair, according to ZhuYayan, the mayor. Altogether 9,141 overseas-funded projects have been negotiated at the past four fairs, with a combined overseas investment of US $ 48.3 billion.

Altogether 1,838 projects using foreign investment were negotiated with a total overseas investment of US $ 9,47 billion. The 1,261 contracts signed at the fourth fair registered a combined pledged overseas investment of US $ 5 billion. The total export and import volume reached US $ 786 million.

1. What is the best title for this passage?

A. The Fifth Fair Will Be Held.                 B. The Fair is Famous.

C. Fairs Attract the World Wide Attention. D. Xiamen is a Trade Zone.

2. How many fingers are there in the logo of the China Fair International Investment and Trade?

A. One.                B. Two.                C. Three.              D. Four.

3. Why is the golden key to success designed as the logo of CFIIT?

A. Because the fair will attract overseas investment to China.

B. Because it is a key to our home.

C. Because it is just like a key.

D. Because the fair is held on August 9.

5. What is the average of the overseas investment on one project in the past four fairs?

A. 0.00380 billion.               B. 0.00529 billion.

C. 0.00513 billion.               D. 0.00397 billion.

某公司培育出一种新的优质抗病虫小麦，下列哪些名称不能作为该小麦申请品种权时所使用的名称（）

A.新兴小麦

B.河北小麦

C.抗病虫小麦

根据肺炎发生的地区可分为_______、_______。

在询问病史时，下列哪一项相对不重要

A．家庭遗传史

B．糖尿病史

C．反复咳嗽史

D．吸烟史