案例四：某男，58岁，右眼视力下降1个月。右眼视力眼前指数，左眼视力1.0。眼底：玻璃体轻度混浊，视 * * 边界不清，轻度隆起，静脉迂曲扩张，呈腊肠样，视网膜大范围片状出血，近视盘的视网膜可见多量片状黄白色渗出，黄斑中心凹亦可见出血渗出。

此例病人的诊断应首先考虑为（）

BLD Inc. produces pure bottled water. The industry has experienced rapid growth as fitness conscious consumers demand these types of products. The growth has attracted many competitors to the industry. However, marketing campaigns to differentiate their products have proven unsuccessful. The main cost to producers is the filtering system that is required to purify the water. The demand for the filtering systems, as a result of industry growth, has led to a reduction in the cost of the systems. Indicate whether the pure bottled water market is best described as a price searcher or price taker and state whether the long-run supply curve is downward-or upward-slopping. Pure bottled water makerLong run supply curve（）①A. Price searcher Downward-sloping ②B. Price takerDownward-sloping ③C. Price searcher Upward-sloping

A. ①

B. ②

C. ③