(2) Xiao Ning put his ear close to the desktop, and the hill tapped the desktop at the same position with the same strength as before, and Xiao Ning could hear the tapping sound;
To sum up, solids can spread sound.
Analysis: Use a table for a long time, with the hill knocking on one side and Xiao Ning listening on the other; Hill on one side with the same strength knocked twice, Xiao Ning put the ear away from the desktop, on the other side close to the desktop to listen; Draw a conclusion by hearing different effects.
Solution:
(1) Xiao Ning takes her ear off the desktop, and the hill taps the desktop on the other side of the table, but Xiao Ning can't hear this tap;
(2) Xiao Ning put his ear close to the desktop, and the hill tapped the desktop at the same position with the same strength as before, and Xiao Ning could hear the tapping sound;
To sum up, solids can transmit sound.
Comments: Solid, liquid and gas can spread sound. This topic examines students' experimental design ability, and the topic is novel!