According to the information in the third paragraph, which of the following improvements made it possible to lengthen the tone produced by the piano?（）
A、The introduction of pedals
B、The use of heavy wires
C、The use of felt-padded hammerheads
D、The metal frame construction
A、The introduction of pedals
B、The use of heavy wires
C、The use of felt-padded hammerheads
D、The metal frame construction
【参考答案及解析】
事实细节题。全文最后一句话中“ the introduction of pedals to sustain tone”表明了踏板的使用使得钢琴的音色延长。
事实细节题。全文最后一句话中“ the introduction of pedals to sustain tone”表明了踏板的使用使得钢琴的音色延长。