not know a single character; absolutely illiterate; 一字不识
I don't know him at all.; He's a perfect stranger to me. 我与他素不相识。
show no understanding of the times; 不识时务
not know how to appreciate favours 不识抬举
learning; knowledge; 学识
foresight and sagacity; 远见卓识
Shi Gonghao 识公浩
have wide learning and a retentive memory; have encyclopaedic knowledge 博闻强识
inscriptions (on bronzes, etc.) 款识
Zhi Ying 识莹
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)