（273）Which statements are true regarding the system-defined moving window baseline in Oracle Database 11g? (Choose all that apply.)

A. It does not allow you to change the moving window size.

B. Adaptive threshold functionalities use it by default to compute statistics.

C. It is created by default with the window size being equal to the AWR retention time.

D. It is created when the first snapshot is collected by the Automatic Workload Repository (AWR).

答案：（B、C）