obj_A <- list(matrix(NA,nrow = 2,2), matrix(NA,nrow = 3,2),matrix(NA,nrow = 2,1));
##  物件結構 list中的各個矩陣維度有可能也是不一樣

##  想填入的值
num <- c(1:12)

##  希望結果是
res_A <- list(matrix(1:4,nrow = 2,2), matrix(5:10,nrow = 3,2),matrix(1:2,nrow = 2,1));