liFE ExpECtAnCy Among ADults 45 AnD 65 yEArs oF AgE By FAmily inComE, sEx, AnD rACE: unitED stAtEs, AvErAgE AnnuAl 1979-89


A、sEquEnCE oF numBErs BEgins 1, 1, 1, 2, 2, 3 AnD thEn rEpEAts this pAttErn ForEvEr. whAt is thE sum oF thE 135th, 136th, AnD 137th numBErs in thE sEquEnCEA．3
B．4
C．5
D．6
E、7