reciprocationn.
rɪ,sɪprə'keʃən
中文n. 交换；往复运动；报答
词根词源
reciprocation (n.)1520s, "mode of expression;" 1560s, "act of reciprocating," from Latin reciprocationem (nominative reciprocatio) "retrogression, alternation, ebb," noun of action from past participle stem of reciprocare "move back, turn back," also "come and go, move back and forth;" from reciprocus (see reciprocal).
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