【多选题】The following are true of the classical Greek theater
A.
Although the names of numerous tragedians are known to us, the plays of only two survive.
B.
At first, the chorus served as both the collective actor and the commentator on the events of the drama; it became increasingly important with the development of Greek theater.
C.
It is one of the most important and famous insitution of Greek civilization.
D.
It rose originally in connection with the worship of Dionysus.