The structure of the vocal tract is very important in forming human voices.

She has a pure heart.

His natural voice is much more beautiful than the recording.

He contributed to many charitable activities during his lifetime.

I have been to Xining in China.

He is seen as a symbol of rebirth.

He was reborn from failure.

Kangaroos are viviparous animals.

His success is due to his tenacity.

He suffered from a transient disease, but recovered quickly.