By observing which dragon had dropped its ball, Chang Heng could ascertain the location of the quake.

通过观察哪条龙的珠子落下，张衡可以确定地震的方位。

youdao

By observing which dragon had dropped its ball, Chang Heng could ascertain the location of the quake.

通过观察哪条龙的珠子落下，张衡可以确定地震的方位。

youdao