1.C【解析】:U={1,2,3,4,5},A={1,2,3,},B={3,4,5},∴AB={3,4},故选C.2.A【解析】z=2+4i)i=(1+2i)(1+i)=-1+3i 1-i3.A【解析】由a⊥(a-b)得a2-a-b=0,ab=a2cos0=.ba_1=-0=60° alblab24.C【解析】 c5a2+b2=2m-2+m=25,得m=9,a2=16,a=4,e=-= a 45.B【解析】由0b>0,所以loga