正式请求某人做某事，或请求某种力量、资源给予支持。
正式要求某人做某事，通常用于严肃或重要的场合。
共 3 个含义,从最常见到最少见,按 CEFR 等级色彩标注。
正式请求或邀请某人做某事，尤其是在公开场合。
"The chairperson called upon the delegates to vote on the resolution."
I call upon you not merely to be tolerant, but to care.
— Nelson Mandela, speech at the United Nations, 1993 (paraphrased from documented address; verify exact wording independently)
调用或利用某种品质、技能或资源。
"She had to call upon all her patience during the long negotiations."
（古旧/文学）拜访某人。
"He called upon the widow to offer his condolences."
比 call on 更正式。常见于政治演讲、法律语言和正式书面语中。也可表示“拜访某人”（古旧/文学用法）。
母语者最常搭配使用的单词。
最常用的五种时态形式。
来自 YouTube 真实视频中 "call upon" 的用法片段 — 点击可在 Looplines 上观看。
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