箱の中を覗き込んだ。

box; case; chest; package; pack; car (of a train, etc.); shamisen case; shamisen; public building; community building; man who carries a geisha's shamisen; receptacle for human waste; feces (faeces); counter for boxes (or boxed objects)

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 direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

peep; peeping; peep show; device with lens mounted on a stand or in a box to view enlarged pictures

to be crowded; to be packed; to be complex; to go into; to put into; to remain (seated); to be plunged into (silence); to do thoroughly; to do intently; to continue in the same state