In fact, unsaturated hydrocarbons, which are not usually present in virgin petroleum, are nearly always manufactured as intermediates during the various refining sequences. 实际上，原油中一般不存在非饱和烃，几乎所有的非饱和烃都是在各种炼制过程中作为中间产品而产生的。
Few of the intermediates or enzymes involved in these conversions have been isolated from higher plants. 在这些转变中包含的少数中间产物或酶已经从高等植物中分离出来。
Note that the overall reaction for this fermentation cannot involve the consumption of nicotin -amide coenzymes or citric acid cycle intermediates. 标明这个发酵的所有反应不包括尼克酰胺辅酶或者三羧酸循环中间产物的消耗。
The intermediates were unable to load these heavy goods. 中型汽车上装载不了这么重的货物。
