186 下列用牛顿一莱布尼茨公式计算积分的做法中,错误的做法一共有-|||-① sqrt ({sin )^3x-(sin )^6x}dx=(int )_(0)^x(sin )^dfrac (3{x)}cos xdx=dfrac (2)(5)(sin )^dfrac (5{x)}x(int )_(0)^1=0.-|||-② (int )_(-1)^1dfrac (dx)(x)=ln (|x|)^1=0.-|||-③ (int )_(0)^pi dfrac ({sec )^2x}(2+{tan )^2x}dx=dfrac (1)(sqrt {2)}arctan dfrac (tan x)(sqrt {2)}(int )_(0)^x=0.-|||-④(int )_(-1)^1dfrac (d)(dx)(arctan dfrac (1)(x))dx=arctan dfrac (1)(x)(|)^1=dfrac (pi )(2)-|||-(A)1个. (B)2个. (C)3个. (D)4个.