Please explain the difference between the following sentences:
- Tom has a busy day so far.
- Tom has had a busy day so far.
Please explain the difference between the following sentences:
The second sentence means that Tom's day, up to the present moment, has been busy. It's specifically about what has happened up until now; it leaves open the possibility that some time later today Tom might have less to do than he has had so far today.
The first sentence is a little bit strange. The only context in which I might say it is if Tom has a schedule of things that he is required to do today, and I'm remarking on the fact that that schedule is unusually full. "I'm sorry, I can't give you an appointment with Tom this afternoon. Tom has a busy day so far, but I can let you know if someone cancels." Even then, I would probably phrase it differently --- "Tom has a busy day today" or something like that.