I understand. The sentence “Tom began playing the piano 4 years ago” can be rewritten in the following ways:
- Tom has been playing the piano for 4 years.
- Tom started playing the piano 4 years ago.
- Tom has been playing the piano since 2019.
- Tom is a pianist who has been playing for 4 years.
- Tom has 4 years of experience playing the piano.
Which version you choose will depend on the context of your writing and the specific meaning you want to convey. For example, if you are writing about Tom’s skills as a pianist, you might say “Tom is a pianist who has been playing for 4 years.” If you are writing about the length of time Tom has been playing the piano, you might say “Tom has been playing the piano for 4 years.”
I hope this helps!