What is the word or phrase?

If 24H in a D => 24 hours in a day.
What does "64S on CB" stand for?

what does the below math rebus puzzle mean?

How can you drop a raw egg from a height onto a concrete floor without cracking it?

Why do we preferably have round manhole covers and not square ones?

Teacher ask the student

'Why are you standing on that chair in music class ?'.

what did student replied ?

what does this picture(rebus) riddle means ?

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

I shave every day, but my beard stays the same. What am I?