两个正数a，b(a＞b)的算术平均值是其几何平均值的2倍，则与a/b最接近的整数是()．
A. 12
B. 13
C. 14
D. 15
E. 16
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Some plants and animals develop superior characteristics so that they may______.
A. help others of their kind get food，shelter and other things needed
B. get into the biological process of adaptation
C. become better adapted to the environments than others of their kind
D. lead to the evolution and production of more and more organisms
“Courses are not designed merely for students to pass exams. ”This means teachers______.
A. want students to fail exams
B. care only about exam grades
C. believe that passing exams is not the only purpose of a course
D. design courses for lectures only
一辆出租车有段时间的营运全在东西走向的一条大道上，若规定向东为正向，向西为负向，且知该车的行驶的公里数依次为-10，十6，+5，-8，+9，-15，+12，则将最后一名乘客送到目的地时该车的位置是()．
A. 在首次出发地的东面1公里处
B. 在首次出发地的西面1公里处
C. 在首次出发地的东面2公里处
D. 在首次出发地的东面2公里处
E. 仍在首次出发地
已知三个质数的倒数和为1879/3495，则这三个质数的和为()．
A. 244
B. 243
C. 242
D. 241
E. 240
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