2010 National Question 2 Free-response Differentiating 2010_退役省自主命题 (2010·理) 2.若复数$z_1=1+i$,$z_2=3-i$,则$z_1\cdot z_2=$ A. $4$B. $2+i$C. $2+2i$D. $3$ Answer keyA ☆ SaveCan't do it, show the explanation查看原卷 →