to use one's head

use one thing for many purposes / work someone hard

counter for pairs of socks, shoes, etc

foot / enough, sufficient / satisfy, fulfill

足: foot / 脚: leg

mobile phone

teleportation

(education) instruction that takes place outside of a classroom (field trip, etc.) / (education) class that takes place in its own specialized room instead of homeroom (such as music or cooking)

moving average

(colloquial) current boyfriend