After much experimentation, the first telephone was exhibited at the Centennial Exposition of 1876 in Philadelphia.

在多次实验后，第一部电话在费城1876年百周年工业博览会上展出了。

youdao

After much experimentation, the first telephone was exhibited at the Centennial Exposition of 1876 in Philadelphia.

在多次实验后，第一部电话在费城1876年百周年工业博览会上展出了。

youdao