题目

下列的实验和实例，不能说明声音的产生或传播条件的是（ ）A.在鼓面上放些碎泡沫，敲鼓时观察到泡沫在不停地跳动B.放在真空罩里的手机，当有来电时，只见指示灯闪烁，听不见铃声C.拿一张硬纸片，让它在木梳齿上划过，一次快些，一次慢些，比较两次的不同D.锣发声时，用手按住锣锣声就停止 答案：【答案】C【解析】A．在鼓面上放些碎泡沫，敲鼓时可观察到碎泡沫在不停地跳动，说明发声体在振动；故A不符合题意；B．放在真空罩里的手机当来电时，只见指示灯闪烁，听不见铃声，说明声音的传播需要介质，真空不能传声；故B不符合题意；C．拿一张硬纸片，让它在木梳齿上划过，一次快些，一请根据句意从方框中选择合适的单词，并用其适当形式填空，使句子通顺。It hero music use three1.Tan Dun is one of the most famous _________ in China.2.It’s __________ (use) to tell her the answer to the maths problem. If you really want to help her, you should tell her how to work it out.3.The reporter wants to know the ___ ___ names because he wants to interview them.4.We were glad to hear that Nick came ___ _____ in the running race.5.Look, the dog is enjoying _____________ meal under the chair.