Jumping down from the chair yesterday was known by her mother.

It is true to have broken his leg just now.

网友的两个句子，是自己创造的吧？两个句子都有错误。

为何要提问这样的问题？而且是自己造句呢？

问题1：know 能接“动名词”作宾语吗？

Her mother knew jumping down from the chair yesterday.（误）

Her mother knew that ....（正）

know 的被动式：be known to，不是by。

动名词，表示一个“事件”，不表示进行概念。

问题2：It is true to do sth. 有这样的语境吗？啥意思呢？先不说完成体是否存在。