The bike is very old, _______ he likes it very much.[ ]
A. and
B. but
C. so
D. or
答案:B
已知曲线C:f(x)=x3-ax+a,
(Ⅰ)若f(x)在区间[1,2]上是增函数,求实数a的取值范围;
(Ⅱ)过C外一点A(1,0)引C的两条切线,若它们的倾斜角互补,求a的值.
含多种黄酮()
A.龙胆
B.石菖蒲
C.川贝
D.桔梗
E.黄芩