11. The cities with the densest population have the highest ratio of police officers to citizens. Such cities also have the lowest rates of property crime without contact between perpetrator and victim. Thus maintaining a high ratio of police officers to citizens can serve as an effective deterrent to at least certain kinds of property crime.
Which of the following, if true, most seriously weakens the argument above?
(A) The quality of training that police receive varies from city to city.
(B) High population density itself makes it difficult to commit a property crime that involves no contact between perpetrator and victim.
(C) Many nonviolent crimes in large cities are drug-related.
(D) A majority of the perpetrators of property crimes in densely populated cities are not apprehended by the police.
(E) Property crimes without contact between perpetrator and victim represent only a small proportion of overall crime.
答案是E,可以解释一下B和E的选项吗
13. Of those person who became teachers in 1968 and who later left the profession, 30 percent today earn salaries above $35,000 a year: of those who became teachers in 1968 and have remained in the profession, only 15 percent today earn salaries above $35,000 a year. These figures indicate how underpaid teachers are today.
The argument above depends on which of the following assumptions about the persons for whom statistics are cited?
(A) At least one-third of the group of persons who have remained in teaching would today be earning more than $35,000 a year if they had left teaching.
(B) The group of persons who left teaching and the group who did not are comparable in terms of factors that determine how much people outside the teaching profession are paid.
(C) Most of those persons who left teaching did so entirely because of the low salaries teachers earn.
(D) As a group, those persons who have remained in teaching are abler and more dedicated than the group of persons who left teaching.
(E) The group of persons who left teaching and who today earn more than $35,000 a year were more capable teachers than the group who remained in the profession.
答案释B可以解释一下B,C,D,E这四个选项吗,各有什么错,和为什么要选B谢谢
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