彼はクラスの中で最年長にあたる。

he; him; his; boyfriend

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

inside; in; among; within; center (centre); middle; during; while

indicates location of action; at; in; indicates time of action; indicates means of action; cause of effect; by; and then; so; indicates continuing action; indicates certainty, emphasis, etc.

eldest

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 be hit; to strike; to touch; to be in contact; to be affixed; to be equivalent to; to be applicable; to apply to; to be right on the money (of a prediction, criticism, etc.); to be selected (in a lottery, etc.); to win; to be successful; to go well; to be a hit; to face; to confront; to lie (in the direction of); to undertake; to be assigned; to be stricken (by food poisoning, heat, etc.); to be afflicted; to be called upon (by the teacher); to treat (esp. harshly); to lash out at; to be unnecessary; to be hitting well; to be on a hitting streak; (in fishing) to feel a bite; (of fruit, etc.) to be bruised; to spoil; to feel (something) out; to probe into; to check (i.e. by comparison); to shave; to be a relative of a person; to stand in a relationship