Each morning I appear to lie at your feet. All day I will follow no matter how fast you run. Yet I nearly perish in the midday sun. What am I?

What walks on four in spring, two in summer and three in winter? What is it which is yours and you do not use, but others always do?

IBM asked for a software engineer position:

How do you weigh an elephant without using a weigh machine?

Can you answer it?