There are a number of preposition words that change the meaning of a phrase when used with a particular word. For example, you can use Thankful with different prepositions, and you will get a different meaning every time. You can see the examples below:
1. Thankful to
Thankful to (Person)
Example: I am very much thankful to your kind favor.
2. Thankful for
Thankful for (thing)
Example: I am really thankful for your timely help.