scratch an itch; 挠痒痒
tweak one's ears and scratch one's cheeks (as a sign of anxiety or delight) 抓耳挠腮
obstruct 阻挠
indomitable; unyielding 不屈不挠
牛津高阶第八版
美国韦氏词典
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维基百科 (自由的百科全书)