下列敘述中正確的是（  ）
Which of the following statements are correct?  
A.在TD-SCDMA系統中每20MS為一個無線幀
In the TD-SCDMA system, every 20ms forms a radio frame
B.在TD-SCDMA系統中每10MS為一個無線幀
In the TD-SCDMA system, every 10ms forms a radio frame
C.每個無線幀可以分成2個子幀
Each radio frame is divided into 2 subframes
D.每個無線幀可以分成4個子幀
Each radio frame is divided into 4 subframes