try:
<body>
except <ExceptionType1>:
<handler1>
...
except <ExceptionTypeN>:
<handlerN>
except:
<handlerExcept>
else:
<process_else>
finally:
<process_finally>
# else执行的条件是try能够正常执行
# finally是一定会执行
无论try是否发生异常，finally总会执行
try无异常，才会执行else
