to spare time away from one's main activity

doppelganger; doppelgänger -- a person's double

a sockpuppet (usu. 假分身) -- an internet account which was created in forums or comments for the purpose of falsely appearing as an outside supporter of a person or organisation when in fact it may be the same person/organisation himself/themselves.

lack; be short of

tired; weary; exhausted

worn-out; spent; used

art; skill; technique

method; tactics; strategy