先生はクラスの前に立っていた。

teacher; master; doctor; with names of teachers, etc. as an honorific; previous existence

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

class

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

ago; before (some event); previously; (minutes) to (the hour); in front (of); before (e.g. the house); head (of a line); front (e.g. of a bus); fore part; in the presence of; helping; portion; privates; private parts

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

to stand; to rise; to stand up; to find oneself (e.g. in a difficult position); to depart (on a plane, train, etc.)