get into a bad habit

1. Once you get into a bad habit, it`s very difficult to get rid of it.
你一旦养成了坏习惯，改掉它是很难的。

2. Once you form/get into a bad habit, it`s very difficult to get rid of it.
你一旦养成坏习惯，改掉它是很难的。

3. Once Once you get into a bad habit, it's very difficult to get rid of it.
once 5，你一旦养成了坏习惯，改掉它是很难的。

4. Once you get into a bad habit then it is difficult/hard to get rid of it.
你一旦染上了坏习惯，就很难除掉。

5.

5. Once you get into a bad habit, you cannot get rid of it easily.
你一旦染上坏习惯，就很难除掉。

6.

6. Once you form/get into a bad habit, it`s very difficult to get rid of/get out of it.
你一旦养成了坏习惯，改掉它是很难的。

7. Once you develop/form/get into a bad habit, it`s very difficult to get rid of/get out of it.
你一旦养成了坏习惯，改掉它是很难的。