能说明元素X的原子得电子能力强于元素Y的原子的事实是（ ）
A．元素周期表中元素X位于元素Y的上一个周期
B．元素X的含氧酸的酸性强于元素Y的含氧酸
C．分别加热H2X、HY至500 ℃，只有HY发生分解
D．元素X与Y同主族，相同温度时其单质与铜反应分别生成Cu2X和CuY
答案：C
A项，Cl元素得电子能力大于C元素，但Cl位于C的下一周期，错误；B项，碳酸的酸性强于次氯酸的酸性，但碳元素得电子能力小于氯元素，故错误；D项，元素X与Y同主族，相同温度时其单质与铜反应分别生成Cu2X和CuY，说明Y得电子能力大于X，故错误。
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| Everyone in business has been told that success is all about attracting and retaining (留住) customers. It sounds simple and achievable. But, 1 , words of wisdom are soon forgotten. Once companies have attracted customers they often 2 the second half of the story. In the excitement of beating off the competition, negotiating prices, securing orders, and delivering the product, managers tend to become carried away. They forget what they regard as the boring side of business- 3 that the customer remains a customer. 4 to concentrate on retaining as well as attracting customers costs business huge amounts of money annually. It has been estimated that the average company loses between 10 and 30 per cent of its customers every years. In constantly changing 5 , this is not surprising. What is surprising is the fact that few companies have any idea how many customers they have lost. Only now are organizations beginning to wake up to those lost opportunities and calculate the 6 implications. Cutting down the number of customers a company loses can make a big 7 in its performance. Research in the US found that a five per cent decrease in the number of defecting (流失的) customers led to 8 increases of between 25 and 85 per cent. In the US, Domino's Pizza estimates that a regular customer is worth more than $5,000 over ten years. A customer who receives a poor quality product or service on their first visit and 9 never returns, is losing the company thousands of dollars in 10 profits (more if you consider how many people they are likely to tell about their bad experience). The logic behind cultivating customer 11 is impossible to deny. "In practice most companies' marketing effort is focused on getting customers, with little attention paid to 12 them", says Adrian Payne of Cornfield University School of Management. "Research suggests that there is a close relationship between retaining customers and making profits." 13 customers tend to buy more, are predictable and usually cost less to service than new customers. Furthermore, they tend to be less price 14 , and may provide free word-of-mouth advertising. Retaining customers also makes it 15 for competitors to enter a market or increase their share of a market. | ||||
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