题目

物理老师自制了“探究真空是否可以传声”的简易装置如图所示，实验时将正在发声的音乐卡芯固定在拔罐器内，用抽气枪逐步抽出罐内空气，关于该实验下列说法正确的是（） A . 音乐卡芯发出的声音不是由振动产生的 B . 音乐卡芯发出的声音尖锐刺耳，说明其声音响度大 C . 抽气时听到的声音越来越小是由于音调变低的缘故 D . 由实验可推理出声音不能在真空中传播All but one ________ take part in the conference ________ tomorrow. [　　] A．is going to; that is to take place B．are going to; that is about to take place C．are going to; that is to be taken place D．are going to; which is to be held