about pyyaml questions!

[Thanatos xiao]

Hi Guys:
Now I use pyyaml to load a yaml file, after I dump this load data,but I
found an questions,before I load the yaml file,the file looks like:

aaaa
-
-b
-c
-
-e
-x

after I dump this data and write file, the file looks like:
aaaa
- -b
-c
- -e
-x

although when dump file, I have set default_flow_style=False

Can the dumped file the same as original file....?

ths.....