Before ____________of synthetic dyes, yarns were often colored by dyes obtained from natural vegetable and mineral matter.
the introduction
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._________________.
内容
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EXCEL2003中，在单元格中输入=20[]AVERAGE（7，9），将显示（）。 A: ATRUE B: B.T. C: CFALSE D: DYES
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of all organic chemical is obtained from crude oil and natural gas. A: 80% B: 99% C: 70% D: 79%
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How are you? You look nice!（） A: AThanks, so are you B: BThanks, so do you C: CYes, I do D: DYes, you are too
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Evidence obtained from observation and experiment is often used to ______ a scientific theory. A: confirm B: confine C: conform D: conceive
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Generally speaking, effective ingredients extracted from natural minerals, animals or plants, as well as drugs obtained by chemical synthesis or biosynthesis are collectively known as chemical drugs.