python菜鸟教程学习7： 条件循环语句

1 if condition_1:
2     statement_block_1
3 elif condition_2:
4     statement_block_2
5 else:
6     statement_block_3

while 判断条件(condition)：
    执行语句(statements)……

while <expr>:
    <statement(s)>
else:
    <additional_statement(s)>

for <variable> in <sequence>:
    <statements>
else:
    <statements>