电视的工作过程和广播相似,声音或图像信号首先通过话筒或摄像机转换成__________,再通过_________加载到射频电流上,通过发射天线发射到空中。
电信号;调制
当牙槽嵴条件差时,采取哪些措施可减少支持组织受力()
A.后牙减数
B.后牙减径
C.选用无尖牙
D.尽可能扩大基托面积
E.使后牙与对颌牙不接触
David is so curious that no one can ________ from finding out what is going on.
A.hold him back
B.hold him up
C.hold to him
D.hold him down