How can knowledge of simple machines be used to someone who has lost an arm or a leg?

cultural/diplomatic relations. most medieval japanese   culture has chinese origins. writing, architecture etc.

well that depends on how deep the hole is. you'd first go through te crust of the earth, then the upper mantle, then the lower mantle then the outer core, then the inner cor then you'd be stuck in the core to melt.

because the vietnam war was fought in an especially brutal and untraditional way

it provided for equal trade rights among nations in china.