質的英文怎么说

質的英文：
hostage
substance
nature
quality

• Plans to spring the hostages have succeeded.
  营救人质的计划成功了。
• The guerrillas threatened to kill their hostages.
  这些游击队员威胁要杀死人质。
• The hostages were freed in the commando raid.
  在突击队的突袭行动中，人质获释。

• Concentration of a substance in solution or the strength of such a substance determined by titration.
  滴定度用滴定的方式测定的一种物质的溶液浓度或这种物质的浓度
• It's a material of substance.
  那是一种坚固的材料。
• To spot or stain, as with a discoloring substance.
  玷污，弄赃因某种褪色物质弄脏、染污

• natural | natural sign
  白键|本位记号
• natural language
  自然语言(指人类语言集团的本族语,与世界语或计算机语言等人造语言相对)
• The method is a natural.
  这方法一定灵。