THREE OLD RIDDLES

1)
They say my first is very bright,
And what they say is true;
But only in my second can
My first be seen by you.
My second would without my first
Be far from being bright;
My whole is what the working man
Welcomes with delight.

2)
Write one hundred and add one,
And then with five unite;
When one and fifty you have joined,
You'll have what is polite.

3)
Both the offspring of shame,
And by modesty bred;
Neither written or printed,
But constantly red.

The symbol of virtue,
And also of vice;
I come when not wanted,
And may - or may not - be nice.

HINTS:
1. One of seven
2. Not 100 + 1

Answers:

1. SUNDAY 
2. CIVIL  (Roman Numerals) 
3. BLUSH