A calculator &gt; needs some-one to tap in the numbers for them to be added, a rock needs &gt; the force of gravity for it to roll down the hill.
(A calculator &gt; needs; some) (it; to roll down; the hill) (them; to be added; ) (a rock; needs; ) (a rock; gt; )
A calculator &gt it them a rock a rock
needs to roll down to be added needs gt
some
the hill