Question

As Preetha was sick so, she did not come to school​ correct the errors

Answer 1

Preetha did'nt came to school as she was sick

hope it helped

I think this is the right answer

Answer 2

Answer:

As Preetha was sick, she didn't come to school.

or

Preetha was sick, so she didn't come to school.

Explanation:

The words AS and SO both justify the reason. Hence, use only one of them.