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一、选择题 1.设a+b+c+d+e=8,a~2+b~2+c~2+d~2+e~2=16,则e的最大值是( )。 (A)1; (B)2; (C)12/5; (D)16/5 2.已知复数z_1,Z_2,Z_3在复平面上的对应点分别为Z_1,Z_2,Z_3,且|Z_1|=|Z_2|=|z_3|=1,z_1+Z_2+Z_3=0,则△Z_1Z_2Z_3为( )。 (A)不等边三角形;(B)等边三角形; (C)直角三角形; (D)钝角三角形。 3.从1开始顺次写出一切自然数,构成N=12…910…99100…9991000…999910000…,那么在N中从左向右第32454个位置上的数字是( )。
First, multiple-choice questions 1. Let a+b+c+d+e=8, a~2+b~2+c~2+d~2+e~2=16, then the maximum value of e is (). (A)1; (B)2; (C)12/5; (D)16/5 2. The corresponding points of the complex numbers z_1, Z_2, Z_3 on the complex plane are Z_1, Z_2, Z_3, respectively. Z_1|=|Z_2|=|z_3|=1, z_1+Z_2+Z_3=0, then ΔZ_1Z_2Z_3 is (). (A) Nonequal triangles; (B) equilateral triangles; (C) right-angled triangles; (D) obtuse triangles. 3. Write all natural numbers sequentially starting from 1 and make up N=12...910...99100...9991000...999910000... Then the number in the 32454th position from left to right in N is ( ).