举个例子
```python
if mark>59:
return '及格'
else:
retrun '不及格'
```第一种写法（个人推荐）
```python
>>> mark1 = 99
>>> mark2 = 59
>>>
>>>
>>> mark1 = '及格' if mark1 >59 else '不及格'
>>> print mark1
>>> 及格
>>>
>>> mark2 = '及格' if mark1 >59 else '不及格'
>>> print mark2
>>> 不及格
```第二种写法
```python
>>> mark1 = ("不及格", "及格")[mark1 > 59]
>>> print mark1
>>> 及格
>>>
>>> mark2 = ("不及格", "及格")[mark2 > 59]
>>> print mark2
>>> 不及格
```第三种写法
```python
>>> mark1 = (lambda:"不及格", lambda:"及格")[mark1 > 59]()
>>> print mark1
>>> 及格
>>>
>>> mark2 = (lambda:"不及格", lambda:"及格")[mark2 > 59]()
>>> print mark2
>>> 不及格
```第四种写法
```python
>>> mark1 = {True: "不及格", False: "及格"}[mark1 > 59]
>>> print mark1
>>> 及格
>>>
>>> mark2 = {True: "不及格", False: "及格"}[mark2 > 59]
>>> print mark2
>>> 不及格
```个人博客：https://blog.codingfly.site