chemicals

• Ammonia is a very reactive chemical .
  氨是很活泼的化合物。
• A chemical group is a submolecular group of atoms .
  化学基因是亚分子的原子集团。
• Chemical degradations are laborious and time-consuming .
  化学降解法复杂且费时间。
• There are chemical fuels that are clean and smokeless .
  有些化学燃料是清洁无烟的。
• About half the chemical engineers have checked out .
  大约有一半化学工程师已经退房。
• Only about 2% of the deposits are chemical grade .
  蕴藏中只有大约2%是“化学级”的。
• Cryoscopy is obtained by classical chemical methods .
  冰点是由经典的化学方法获得的。
• Allelopathic chemicals are ecologically important .
  异株克生化合物在生态学上很重要。
• These substances include many commonly used chemicals .
  这些物质包括许多常用的化学品。
• Chemical thinners add another to the arsenal of sprays .
  化学疏除剂已列入农药的宝库中。