ecological niches and their resident species

The X-ray finding of duodenal ulcers is____. A: niches B: bulb deformation C: mucosal disorder and tortuosity D: pyloric spasm

The direct X-ray finding of duodenal ulcers is ________. A: niches B: bulb deformation C: mucosal disorder and tortuosity D: pyloric spasm

Through concentrated marketing, a firm achieves a strong market position because of its greater knowledge of consumer needs in the niches it serves and the special reputation it acquires.

“长尾理论”的关键组成部分包括() A: 热卖品向niches转变 B: 富足经济 C: 许多小市场集合成一个大市场 D: 网络效应

下列哪个不是长尾理论的含义 A: 热卖品向利基（niches）的转变 B: 富足经济（theeconomicsofabundance） C: 供给方规模经济 D: 许许多多小市场聚合成一个大市场

Which of the following is the incorrect description of malignant ulcers? A: In posteroanterior view, the niche is round or unrepresentative round, surrounded by convex curves B: Relatively large cancerous ulcer with shallow depth C: In posteroanterior view, the contour of the niche is outwards, surrounded by concave curves D: Large areas of mucosal folds around the ulcer are destroyed and disappeared E: Mucosal folds are concentrated towards the niches, and they are interrupted halfway before they arrive