Before ____________of synthetic dyes, yarns were often colored by dyes obtained from natural vegetable and mineral matter.
举一反三
- Before ____of<br/>synthetic dyes, yarns were often colored by dyes obtained from<br/>natural vegetable and mineral matter. A: introducing B: introduction C: the introduction D: introducing that
- All mineral water is ‘natural’, coming straight from a natural spring.
- Evidence obtained from observation and experiment is often used to _____ a scientific theory.
- It is said that synthetic fiber (合成纤维) is not as good as natural fiber. Natural fiber is said to be __________ synthetic fiber. (superior)
- 名词：原油，a mineral oil obtained from below the surface of the Earth, and used to produce pertrol , paraffin , and various chemical substance._________________.