Crick, who saw a photo only of Dr. Franklin's B form, immediately recognized that DNA consisted of two parallel helixes, or twisted chains, running in opposite directions.
克里克见过富兰克林的B型照片，立即发现DNA包含反向旋转的两个并列螺旋列或叫扭曲链。
2
The sequencing optimal decision of parallel procedure chains is one of the focuses of the theory of project planning and control at present.
平行序链的顺序优化问题一直是目前网络计划优化理论研究的焦点问题之一。
3
Why do so many earthquakes originate in this belt? This is a region of young, growing mountains and deep ocean trenches which invariably parallel mountain chains.