如何组合for循环语句？

array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
sum = 0
for row in array:
    for element in row:
        sum += element
print(sum)

list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
for item1 in list1:
    for item2 in list2:
        print(item1, item2)

dict = {'a': [1, 2, 3], 'b': [4, 5, 6], 'c': [7, 8, 9]}
sum = 0
for key in dict:
    for element in dict[key]:
        sum += element
print(sum)