They are playing a waltz by Strauss.是什么意思？

They are playing a waltz by Strauss.

他们在演奏一首斯特劳斯的圆舞曲.

they

pron. 他/她/它们，人们，大家，政府，当局，她们；

例句
The storms had abated by the time they rounded Cape Horn.
他们绕过合恩角时，暴风雨已经减弱。

are

vi. （用于第二人称单复数现在时，第一、三人称复数现在时）是；n. 公亩（等于100平方米）；

例句
We are scared to abandon ourselves to our feelings in case we seem weak or out of control.
我们不敢放纵自己的情感，以免显得太过软弱或缺乏自制。

playing

v. 演奏( play的现在分词 )，演出，参加比赛，捉弄；

例句
By his own admission, he is not playing well...
他自己承认表现欠佳。

waltz

n. 华尔兹舞，华尔兹舞曲；vt. 跳华尔兹舞；vi. 大摇大摆地走，轻易完成；

例句
Her singing of " Evening Waltz " was easy and lively, well - balanced and appropriately controlled in volume.
她唱的 “ 晚会圆舞曲 ” 轻松愉快, 层次分明,音量的控制也恰到好处.

by

prep. 在…旁边，表示方式，由于，经过；adv. 经过，表示保留或保存时用，短暂拜访；

例句
...expensive make-up that we saw being advertised by a beautiful model...
我们所见的由一位漂亮模特代言的昂贵化妆品

Strauss

[人名] 斯特劳斯，[地名] [美国] 斯特劳斯；

例句
Levi Strauss says counterfeits of the company's jeans are flooding Europe.
利维·施特劳斯称仿冒其公司品牌的牛仔装正充斥着欧洲市场.