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...
Before signing, he covenanted that he would remain in possession.签字以前, 他要求以保留所有权为条件.They covenanted that their hostages would be present.他们保证他们的人质到场.They covenanted in loyalty to the king.他们缔结盟约以效忠国王....