题目

—Is Jenny on Friday? —Yes, she is. She has many things to do. She has no time to meet you. A . free B . busy C . fine 答案：B关于声现象，下列说法正确的是A．只要发声体振动，我们就可以听到声音　 B．一切能发声的物体都在振动　 C．声音在液体中比在固体中传播得慢些　 D．振动停止了，声音能继续传播