Silly Viper

What is always in front of you but can’t be seen?

What month of the year has 28 days?

People make me, save me, change me, raise me. What am I?

What can fill a room but takes up no space?

What does A stands for in the word ASAP:
____SOON ____ POSSIBLE

IF THERE ARE 20 PERSONS IN A HALL AND 15 PERSONS WERE SHOT, WHAT TOTAL OF PEOPLE ARE THERE