This amazing picture shows a rare phenomenon called a roll cloud which tend to form ahead of a cold front and can stretch for miles.
这张惊人的图片展示了一种叫做云卷的罕见现象，它往往形成于冷锋之前，并能延伸数英里远。
2
Where the east coast of s America is little affected during the 7 of 10 s America roll (which is in process though moving slowly) it does undergo a stretch.
小s的美国东海岸是在7 10秒美国卷(这是在过程中，虽然移动缓慢)它接受一个舒展的影响。
3
The paper analyzed the causes of roll displacement on mini-stretch reducing mill and the influences of displacement on external-surface quality of steel pipe.