-------------------------------------homework1----------------------------------------------------

sum = 0

L = list(range(101))

for x in L:

    sum = sum + x

print(sum)

-------------------------------------homework2----------------------------------------------------

L = ['Bart', 'Lisa', 'Adam']

a = 0

while a <= 2:

   print("hello, %s!"%L[a])

   a = a + 1

-------------------------------------homework3----------------------------------------------------

死循环：

a = 1

while a >= 1 :

  print(a)

  a = a +1