ImportError：无法导入名称X

我有四个不同的文件，分别命名为：main，vector，entity和physics。我不会发布所有代码，而只会发布导入代码，因为我认为这就是错误所在。 （如果需要，我可以发布更多信息）

I have four different files named: main, vector, entity and physics. I will not post all the code, just the imports, because I think that's where the error is. (If you want, I can post more)

主要：

import time
from entity import Ent
from vector import Vect
#the rest just creates an entity and prints the result of movement

实体：

from vector import Vect
from physics import Physics
class Ent:
    #holds vector information and id
def tick(self, dt):
    #this is where physics changes the velocity and position vectors

向量：

from math import *
class Vect:
    #holds i, j, k, and does vector math

物理：

from entity import Ent
class Physics:
    #physics class gets an entity and does physics calculations on it.

然后我从main.py运行，出现以下错误：

I then run from main.py and I get the following error:

Traceback (most recent call last):
File "main.py", line 2, in <module>
    from entity import Ent
File ".../entity.py", line 5, in <module>
    from physics import Physics
File ".../physics.py", line 2, in <module>
    from entity import Ent
ImportError: cannot import name Ent

我是Python的新手，但是使用C ++已有很长时间了。我猜测该错误是由于两次导入实体引起的，一次是在实体中，一次是在物理中，但是我不知道解决方法。谁能帮忙？

I am very new to Python but have worked with C++ for a long time. I'm guessing that the error is due to importing entity twice, once in main, and later in physics, but I don't know a workaround. Can anyone help?