if语句：
a = 66
b = 200
if b > a:
  print("b is greater than a")

Elif：
a = 66
b = 66
if b > a:
  print("b is greater than a")
elif a == b:
  print("a and b are equal")

Else：
a = 200
b = 66
if b > a:
  print("b is greater than a")
elif a == b:
  print("a and b are equal")
else:
  print("a is greater than b")

a = 200
b = 66
if b > a:
  print("b is greater than a")
else:
  print("b is not greater than a")

if else ：
a = 200
b = 66
print("A") if a > b else print("B")

a = 200
b = 66
print("A") if a > b else print("=") if a == b else print("B")

And：
a = 200
b = 66
c = 500
if a > b and c > a:
  print("Both conditions are True")

嵌套 If：
x = 52

if x > 10:
  print("Above ten,")
  if x > 20:
    print("and also above 20!")
  else:
    print("but not above 20.")

pass：
a = 66
b = 200

if b > a:
  pass