nonplus

The unexpected question reduced the speaker to a nonplus.

用法提示：nonplus 为名词，表示‘困惑、不知所措’，在句中作介词 to 的宾语，说明陷入的窘境。

For a moment, she was in a complete nonplus, unable to choose between the two offers.

用法提示：nonplus 作名词，与 in a ... 搭配，描述一种困惑、无法决断的状态。

His nonplus was obvious when the teacher asked him to explain his own diagram.

用法提示：nonplus 在句中作主语，直接表示‘困惑、不知所措’这种状态。