问题1：评价题 The FMD， foot and mouth disease is caused by a virus transmitted to humans by deer ticks. Generally, deer ticks pick up the virus while in the larval stage by feeding on infected black mice. However, certain other species on which the larvae feed do not harbor the virus. If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the virus would likely decline.
答案：Whether the deer tick population's size is currently limited by the capability of animals for the tick's larval stage to feed on
能否帮我具体解释推导一下这之间的逻辑关系呢？
问题2：加强题 An unexpected increase in the production of elephant ivory artifacts on the Nigerian coast of North Africa occurred in the eleventh century. Historians clarify this increase as the consequence of an area opening up as a new source of ivory and argue on this basis that the important medieval trade between North Africa and West Africa began at this period.
each of the following if true provides some support for the author's account described above except:
a. in west africa gold coins from nigerian north africa have been found at a tenth-century but at no earlier sites
b. t he many surviving letters of pre-eleventh-century north african merchant include no mention of business transactions involving east africa
c. excavations in west africa reveal a eleventh-century change in architectural style to reflect north african patterns
d.Documents from Nigerian Europe and North Africa that date back earlier than the eleventh century show knowledge of West African animals.
e.east african carvings in a style characteristic of the eleventh century depict seagoing vessels very different from those used by local sailors but of a type common in the nigerian
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发表于 2013-3-9 17:30:28
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