严肃地

She spoke with great seriousness of the hardships she had endured.

她非常肃地讲述了自己经历。

Joseph gravely heard them out but never offered advice.

约瑟夫肃地听他们说完但是却没有提出任何建议。

Despite their protestation, they were glad to accept our help.

尽管他们肃地表明了态度，但他们仍乐于接受我们援助。