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to throw into; to toss into
to throw-in; to play a throw-in
荷物をトランクに放り込んで出発した。
I threw my luggage into the trunk and departed.
読み終わった手紙を丸めてゴミ箱の中に放り込んだ。
I tossed the letter into the trash can.
洗濯物を洗濯機に放り込んで外出した。
I threw the laundry into the washing machine and went out.