可视电话(Video Phone),下行占用()个SF=16的码道,上行占用()个SF=()的码道。
A.2/1/8
B.8/1/2
C.8/1/8
D.2/1/4
参考答案:B
一个几何体的主视图、左视图、俯视图都是正方形,那么这个几何体一定是( )。
“I know she was in because I heard her radio, but she didn’t open the door.” “She___the bell.”
A.may not be hearing
B.may not have heard
C.must not have heard
D.must not be hearing