常见例句双语例句There are two manufacturing methods of pyridine bases: extraction from coal tar and catalytic synthesis from ammonia, formaldehyde and acetaldehyde.吡啶碱的生产方法主要有两种：一是从煤焦油中提取；二是从氨和甲醛、乙醛的合成过程中获得。 返回 acetaldehyde ammonia