【单选题】

In the United States the most popular form of folk dancing since the early days has been square dancing. In early times, when men and women worked in groups to (21) a barn(谷仓) for harvest crops, they danced when the work was done. The music (22) from a violin for the most part.But if there was no one to play an instrument(乐器), clapping(击掌) was used to (23) the rhythm(节奏) by which to dance. The early settlers(移民) danced in a store, in a barn, or in a farm kitchen.

After some years (24) , square dancing became (25) popular in cities and towns, but it (26) popular in the country. Then it became popular in the cities once again. Today in (27) parts of the United States you will find some school, club, or other group that is square dancing for fun.
A、square is formed by four couples(对，双) who stand (28) the center of the square.Each couple stands on one (29) of the square, the boy on the left and the girl on the right.
The "caller" is an important part of the (30) since he tells the dancers which steps to do. If the dancers do not know the steps, he teaches them. It (31) time to learn to be good caller, and good callers are always in demanD、
Large or small groups of people can dance at one time. Sometimes 800 or 1,000 people may be dancing at the (32) time. Or there may be only one square of (33) people.
Costumes(服装) are worn by some who square dance. This (34) the dancing more colorful to watch. The costumes vary(不同) from place to place. Women often wear full skirts of various colors with pretty blouse(罩衫). Men may have colored skirts and western trousers which they wear (35) when square dancing.
A．causes
B．makes
C．does
D．lets