[Grammar] Which sentences are correct?

[OOMarijaOO]

Before being classified, the data is stored in the computer memory. OR Before classifing, the data is stored in the computer memory.

Before being published, the paper has to be revised several times. OR Before publishing, the paper has to be revised several times.

Before being stored, the data must be converted into digital form. OR Before storing, the data must be converted into digital form.

 

[billmcd]

Before being classified, the data is stored in the computer memory. OR Before classifying, the data is stored in the computer memory.

Before being published, the paper has to be revised several times. OR Before publishing, the paper has to be revised several times.

Before being stored, the data must be converted into digital form. OR Before storing, the data must be converted into digital form.

All are OK.