python如何把两个列表合并

list2 = [4,5,6]

list_new = []

for item in list1:

  list_new.append(item)

for item in list2:

  list_new.append(item)

print list_new

a = [1,2,3]

b = [4,5,6]

c = zip(a,b) //c = [(1,4),(2,5),(3,6)]

list_new = [row[i] for i in range(len(0)) for row in c]

a = [1,2,3]

b = [4,5,6]

c = a + b