solemn的名詞形式是什么

　　例句：

　　I made a solemn promise that I would return.

　　我鄭重承諾我會回來的。

　　His behaviour was not in keeping with the solemn occasion.

　　他的舉止與這莊嚴的場合不協調。

　　This is a solemn curtsy in the party.

　　這是一個在聚會中的隆重的禮節。