back-and-forth基本解释
来回地; 反复地
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名词: back-and-forth
【hao86.com留学群】
名词: back-and-forth
"he traveled back and forth between Los Angeles and New York"
"the treetops whipped to and fro in a frightening manner"
"the old man just sat on the porch and rocked back and forth all day"