cān / guān / zhè / cì / zhǎn / lǎn / shí / wǒ / cái / zhī / dào / huàn / qí / bìng / bú / shì / pǔ / tōng / de / qí / bīng

参观这次展览时，我才知道宦骑并不是普通的骑兵。

It was only when I visited this exhibition that I learned horse guards were not ordinary cavalry.