What common phrase is represented by the below lines

Easy going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Medium going:
Weak, 'I'm going.'
Tough, 'I'm staying.'

Tough going:
Weak, 'I can't do it, I'm staying!'
Tough, 'Let's get going.'

It's a test that will check your IQ.

Suppose you have one 11 minute hourglass and one 13 minute hourglass.

Can you measure exactly fifteen minutes using them ?

I possess a head

I flaunt a tail

But I don't have mouth or legs

Can you find out who I am?

What happened when the wheel was invented?

How will you measure 15 minutes using two hourglasses of 7 minutes and 11 minutes respectively?

What demands an answer, but asks no questions

The dirtier I get, the whiter I look. Who am I?

I have an eye but still cannot see.

Who am I?

A four-digit number (not beginning with 0) can be represented by ABCD. There is one number such that ABCD=A^B*C^D, where A^B means A raised to the B power. Can you find it?

what does this below rebus represent identXQQQQQME