2021 National Question 4 Single-choice Differentiating 2021_全国乙卷 (2021·理) 4.设函数 $f(x)=\frac{1-x}{1+x}$ ,则下列函数中为奇函数的是 A. $f(x-1)-1$B. $f(x-1)+1$C. $f(x+1)-1$D. $f(x+1)+1$ Answer keyB ☆ SaveCan't do it, show the explanation查看原卷 →