The president nodded soberly, motioning the ambassador to a chair.是什么意思？

The president nodded soberly, motioning the ambassador to a chair.

总统沉着地点了点头, 作了个手势请大使坐下.

the

art. 指已提到的人（物），指说话人与听者已知的人（物），用于独一无二的事物前，与形容词最高级和序数词连用；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

president

n. 校长，总统，总裁，董事长；

例句
The President described the killings as an abominable crime...
总统称这些血案为令人发指的罪行。

nodded

v. 点头( nod的过去式和过去分词 )，打盹，打瞌睡，点头致意；

例句
Mitzi nodded a perfunctory acknowledgement as her glass was filled.
杯子被倒满时米芝敷衍性地点头示意。

soberly

adv. 清醒地，冷静地，严肃地，朴素地；

例句
But we should realize soberly that the merged HE institutions do not shut efficaciously.
但我们也应清醒地认识到高校合并并非一合则灵,一并则优.

motioning

vt. 打手势（motion的现在分词形式）；

例句
Crossing a forest, he saw a lion motioning him to stop.
穿过一片森林的时候, 他看到一只狮子向他示意,让他停下来.

ambassador

n. 大使，使节，（派驻联合国等国际组织的）代表，特使，[比喻]使者；

例句
...the American Ambassador at the United Nations.
美国驻联合国大使

to

prep. 向，朝着，到，关于，属于；adv. 朝一个方向的，到某种状态，关闭；

例句
I suggest you leave it to an expert...
我建议你把它留给专家来解决。

chair

n. 椅子，大学教授职位，主持会议的主席（的席位或职位），讲座；vt. 主持，使…入座，使就任要

例句
She rose from the chair and gazed across at him.
她从椅子上站起身，远远地看着他。