2008 National Question 4 Single-choice Differentiating 2008_quanguo_old_i 4.(5分)设a∈R,且(a+i)<sup>2</sup>i为正实数,则$a=$( ) A. 2B. 1C. 0D. ﹣1 Answer keyD ☆ SaveCan't do it, show the explanation查看原卷 →