孩子们被气球完美的圆形所吸引。

The children were fascinated by the perfect ___rotundity of the balloons.

这位歌剧演员的声音具有令人愉悦的圆润感。

The opera singer's voice carries a delightful ___rotundity.

圣诞老人以他的圆胖体型而闻名。

Santa Claus is famous for his ___rotundity.