Newborn calves are not afraid of tigers. -- Young people are fearless.; Fools rush in where angels fear to tread.; Newborn calves make little [light] of tigers.; The newborn calf fears no tigers. 初生之犊不畏虎。
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)