Hangman: Reverse Edition

Put a P, then Brahma, Vishnu and Shiva will turn a goddess into this.

Put an R, you speak it more than writing it.

Put a T, I become e-learning.

Put a G, then I become a floor.

If you’re new to reverse hangman:

The final answer will be a string with one letter blank which can be filled in in several different ways to form a valid word (eg "_it" can make lit, fit, kit, bit, etc.)

In your answer, please give the string with the missing letter and explain each line.