What do typing on a computer, lifting a box, and putting on a sweater have in common?

For each one . . .

-- some part of your body has to move

-- you convert some chemical energy into kinetic energy when you make muscles move  

-- a human being can do it but an animal can't.

We, maybe a monkey can lift a box.  2 out of 3 ain't too bad.

i would think it's food chain

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.