The mass fraction of n - butene in mixed C 4 from catalytic cracking after etherized was approximately 40 %.醚化后的催化裂化混合C4中含有质量分数约为40%的正丁烯,是生产丙烯的优质原料....
He despairingly abandoned his search.他绝望地放弃了寻找.Scarlett thought despairingly that a plague of locusts would be more welcome.思嘉绝望地觉得这比经受一次蝗灾还要可怕.‘You promised me love!’ he cried despairingly.“你答应过爱我的！”他绝望地哭喊道。'You pr...