Comprehensions and Generators - General Questions

What is the output of the following code?

print([(i, j) for i in range(2) for j in range(2) if i != j])

What is the output of the following code?

matrix = [[1, 2], [3, 4]]
print([row[i] for i in range(2) for row in matrix])

Which brackets create a generator expression?

What is the output of the following code?

print([(x, y) for x in range(2) for y in range(2) if x != y])

What is the output of the following code?

print([x for x in range(10) if x % 3 == 0])