盘旋 pánxuán 经常 jīngcháng 改变 gǎibiàn 回转 huí zhuǎn 方向 fāngxiàng 和 hé 节距.

Convolutions frequently alternate in direction of rotation and vary in pitch.

戒 jiè 掉 diào 烟 yān 酒 jiǔ 是 shì 改变 gǎibiàn 你 nǐ 不良 bù liáng 健康状况 jiàn kāng zhuàng kuàng 的 de 唯一 wéiyī 途径 tújìng .

Abstention from drinking and smoking is the only way to improve your poor health.

他们 tā men 的 de 状况 zhuàngkuàng 现在 xiànzài 改变 gǎibiàn 了 le ; 汤姆 Tāng mǔ 穷 qióng 了 le ,本 běn 富 Fù 了 le .

Their conditions are now reversed; Tom is poor and Ben is rich.

基因突变 jī yīn tū biàn 是 shì 指 zhǐ DNA密码 mìmǎ 的 de 改变 gǎibiàn .

Gene mutations are alterations in the DNA code.