1.填空题 (1)设f(x)在[a,证连续， a≤x≤b (2) _dt (3) (4) tantdt lim 0 x→0 x2 f x( ) [ , ] a b a x b   d ( )d d x a f t t x =  d ( )d d b x f t t x =  2 0 d sin d d 1 cos x t t t x t = +  sin 2 0 d 1 d d x t t t x + =  0 2 0 tan d lim x x t t → x =  1.填空题 (1) 设 上连续， ， ; . . . . 在 (2) (3) (4)