(x1,y1),(x2,y2)和(x3,y3)是位于同一条无差异曲线上的任意三点。另有t满足0≤t≤1,那么在以下()情况下,一定存在一价格向量使得消费者均衡点有无数个。
A. t(x1,y1)+(1-t)(x2,y2)>(x1,y1)
B. t(x1,y1)q-(1-t)(x2,y2)>-(x2,y2)
C. t(x1,y1)+(1-t)(x2,y2)~(x3,y3)
D. t(x1,y1)+(1-t)(x2,y2)<(x1,y1)
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What do we mean by a perfect English pronunciation?In one【11】there are as many different kinds of English as there are speakers of it. No two speakers speak in exactly the same【12】We can always hear different forms between them, and the pronunciation of English【13】a great deal in different geographical areas. How do we decide What sort of English to use as a model?This is not a question that can be【14】in the same way for all foreign learners of English.【15】you live in a part of the world like India or West Africa, where there is a long tradition of speaking English for general communication purposes, you should【16】to acquire a good variety of the pronunciation of this area. It would be a fashion in these circumstances to use as a model BBC English or anything of the sort. On the other hand, if you live in a country【17】there is no traditional use of English. You must take as your model some form. of【18】English pronunciation. It does not【19】very much which form. you choose. The most【20】way is to take as your model the sort of English you Can hear most often.
(11)
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