Student or Learner
I was just reading a Standard test question with the following two options:
The best thing to do is leave it alone, let it dry and ....
The best thing to do is (to) leave it alone,.....
I thought the (to) is required in the example above but the answer explanation says it is not. Is that correct ? Is there any rule about when you want to use (to) in this case ?
It's fine with or without 'to'.