学校の決まりは守らないといけない。

school

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

rule; regulation; settlement; conclusion; end; agreement; arrangement; habit; custom; habitual way; countenance in front of another person; face; love relationship between a customer and a prostitute

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

to protect; to guard; to defend; to keep (i.e. a promise); to abide (by the rules); to observe; to obey; to follow

if; when; and; with; particle used for quoting (with speech, thoughts, etc.); quoting particle; promoted pawn; indicates question (sentence end)