Answer:
‘Shh! Don't tell anyone', she whispered.
The answer should be whispered because the speaker said “shh” which implies a private conversation at a minimal volume
Billy tiptoed up the stairs so as not to wake his parents up.
Whispered would be the best verb to insert in the sentence because tiptoeing is very silent and would not disturb his sleeping parents.
Tom glared at his sister for saying the wrong thing to his boss.
The best choice would be glared because Tom would be unhappy and express a negative action towards the look he gave his sister for saying the wrong this to his boss.
I hope this helps! :)