Question

not only my brother but also i ( ) good at painting. both of

Answer 1

第一个空是 填am, 在 not only ..but also ...这个修饰的是主语时，谓语动词的数取决于就近原则，由于最近是I, 所以用am.

第二个空是are, 。。。both是两者都的意思，谓语动词用复数。