If something is purportedly true, that is the story being offered — someone claims it — and you are not putting your own name on that story. The word quietly says: this is what is said, and it may not be so.

If something is purportedly true如果某件事「據稱」是真的, that那 is the story being offered就是被提出來的說法 — someone claims it有人這麼宣稱 — and而 you你 are not putting your own name on that story並沒有把自己的名字放到那個說法上（不掛保證）。The word這個詞 quietly says悄悄地在說: this is what is said這是別人說的, and而 it它 may not be so未必是真的。

A man is purportedly a doctor (that is the claim; you have not checked). A painting is purportedly from the eighteenth century.

A man一個男人 is purportedly a doctor據稱是醫生 (that is the claim那是別人的說法; you have not checked你並沒有查證)。A painting一幅畫 is purportedly from the eighteenth century據稱來自十八世紀。

It is a careful, slightly formal adverb, common in news and in any talk where you do not want to swallow a claim whole. It is cooler than supposedly, which can already sound as if you think the claim is thin; purportedly just holds the claim at arm’s length.

It它 is a careful, slightly formal adverb是個謹慎、稍微正式的副詞, common in news常出現在新聞裡 and還有 in any talk任何 where you do not want to swallow a claim whole你不想全盤接受某個說法的場合。It它 is cooler than比 supposedly冷靜、疏離, which can already sound as if you think the claim is thin那個字聽起來可能已經帶著你覺得這個說法站不住腳的味道; purportedly「purportedly」 just holds the claim at arm's length只是把這個說法保持在一定距離之外。

You use it when the claiming is the point, not when you yourself are sure.

You你 use it會用它 when the claiming is the point當重點是「有人這麼宣稱」的時候, not when you yourself are sure而不是當你自己很確定的時候。