汉英词典
Chinese-English Dictionary
MEANING OF 唱双簧
唱双簧 (唱雙簧)
lit. to sing a duet / fig. to collaborate with sb / also used satirically: to play second fiddle to
chàng () shuāng huáng
EXAMPLE SENTENCES

所谓的天长地久、只不过是两个人在唱双簧

The so-called forever, also is only two men in the duet.