Help me see if there are any grammatical mistakes in the following German sentences. Is vocabulary used properly? thank you

1.sowohl als auch often connects sentence elements, but does not connect sentences. It can be changed to nicht nur sondern auch.

You see, many students spend a lot of time in their blogs. Darum can be followed by Dass clause.

His research has been affected. Leiden was more sick and unlucky.

6. Do you think potential blogs have potential? ndig bewusst。