This dance is known __ country music．

经典音乐乡村音乐,
经典无需解释,范围更大
乡村音乐曲调很好听

Country music is a blend of popular musical forms originally found in the Southern United States and the Appalachian Mountains.It has roots in traditional folk music,Celtic music,gospel music,and old-time music and evolved rapidly in the 1920s.The term country music began to be used in the 1940s when the earlier term hillbilly music was deemed to be degrading,and the term was widely embraced in the 1970s,while country and western has declined in use since that time,except in the United Kingdom and Ireland,where it is still commonly used.[1]
In the Southwestern United States a different mix of ethnic groups created the music that became the Western music of the term country and western.
Country music has produced two of the top selling solo artists of all time.Elvis Presley,who was known early on as “The Hillbilly Cat” and was a regular on the radio program Louisiana Hayride,went on to become a defining figure in the emerging genre of rock 'n roll.Contemporary musician Garth Brooks,who has interupted his career to raise his children,is the top-selling solo artist in U.S.history
While album sales of most musical genres have declined,country music experienced one of its best years in 2006,when,during the first six months of the year,U.S.sales of country albums increased by 17.7 percent to 36 million.Moreover,country music listening nationwide has remained steady for almost a decade,reaching 77.3 million adults every week according to the radio-ratings agency Arbitron Inc.
The term "country music" is used to describe many styles,genres,or subgenres.

给你个网址参看试试：http://en.wikipedia.org/wiki/Country_music

a what I am interested in是主语从句,谓语动词单数

Ed:(Do) you (like) country music,Sarash?
Sarah:Yes,I (like ) it a lot.I'm a real fan of Garth Brooks.
Ed:Oh,( Does) he piay the guitar?
Sarah:Yes,he ( does) .he's my favorite musician.
2.
Anne:( What) kind of music (do ) your parents (like ),Jason?
Jason:They ( like) calssical music.
Anne:Who ( do) they (like Mozart?
Jason:NO,they ( don't) like jim very much.They prefer Beethoven.
3.
Scott:Teresa,( do) you ( like) Christina Aguilera?
Teresa:No,I ( don't) .I can't stand her.I like pink.
Scott:I don't konw her.What kind of muice ( does) she sing?
Teresa:She (sings ) pop songs.She's really great!

1-3 DDC

1-4 DCCD

此句子=it is known that this dance is performed to country music.
大家知道这个舞蹈是和着乡村音乐表演的.

to be,这里是动词不定式的被动语态.没有具体的解释.