已知:a与b互为相反数，c与d互为倒数，x=3(a-1)-(a-2b)，y=cd+c(a+b). 求3x-2y的值.

My father _____ gave me some exercises and told me to do them _____.  [ ]

A. myself, by myself

B. himself, by myself

C. herself, by herself

D. yourself, by yourself