Question

she ____ have reached school by now

Answer 1

She might have reached school by now

Answer 2

Fill in the blanks:

   She ___ have reached school by now.

There are multiple answers possible here.

   She would not have reached school by now.
   She would have reached school by now.
   She could (n't) have reached school by now.
   She might (not) have reached school by now.
   She should have reached school by now.
   She must have reached school by now.

The exact word (auxiliary verb) depends on the meaning (intended).