题目(选择题,4分)函数y=tan x的导数是()。A. sec^2xB. cos^2xC. sin^2xD. cot^2x(选择题,4分)函数$y=\tan x$的导数是()。A. $\sec^{2}x$B. $\cos^{2}x$C. $\sin^{2}x$D. $\cot^{2}x$题目解答答案A. $\sec^{2}x$