英语中有两种冠词，定冠词(the)和不定冠词(a, an)。使用名词时，如果前面需要加冠词，就要考虑选择哪类冠词，这取决于名词本身。
（1）表明特定事物。The culture that was contaminatedwas discarded. \ The Nobel prizewinner in 2006 inmedicine…
（2）与短语连用。…in the presenceof … \ …in the absence of…
（3）用以复述前文提到过的事物。The technician looked at the sample we had measured earlier. \ Themethods described previously.
（1）表示群体中的一员或第一次提到的事物。A scientist needs to write well.\ She used an aliquot to determineDNA concentration.
（2）表示一类事物。A protein can be made up of manydifferent amino acids.
（1）复数名词且第一次提到。She collected samples for DNA isolation.
（2）专有名词或抽象名词。Berlin was a divided city. \ Degradationoccurs after 24 hrs. \ In conclusion, we determined that…
当将专有名词或抽象名词作一般名词使用时。The Berlin that was divided is gone. \ The degradation we observed Occurredafter 24hrs. \ The conclusion of thediscussion should summarize the results. \ Aconclusion about X cannot be drawn.
练习：在需要的地方加入正确的定冠词或不定冠词。
1. Oscillatory behavior was reducedin_________presence of a ring electrode.
2. Sea urchin fertilizationis_________model system in developmental biology.
3. Therefore,_______hypothesis wepresented previously is further confirmed.
4. Back to_______nature.
5. ________inorganic chemistry provesto be a very interesting subject.
6. Can you name_________inorganicmolecule?
7. Conversion of__________CK riboside to thebase can be regarded as the last step in the pathway.
8. The data for oxidation of hydrogen at thePt electrode were obtained in______ Absence of chloride ions.
9. _________theoretical studies cited earlierdepict a variety of different patterns in oscillating media.
10. Here we discuss ________physical-chemicalmechanisms leading to pattern formation in electrochemical systems.
11. Title: ____Roleof_____Physical Activity on_____Severity of Diabetes.
12. Title: _____OrbitalReconstruction and___Covalent Bonding at ____Oxide Interface
13. Title: _____Correlation of_____Highest–Energy Cosmic Rays with_____Nearby Extragalactic Objects
14. Figure 4:_____effectof____temperature on______ctx expression.
15. ______lichens consist of algae orcyanobacteria and fungi, which coexist in symbiosis.
16. _______rainfall in____Saharadesert occurs rarely.
17. _____average rainfallin____Sahara desert is less than 25 mmper year.
18. Under_____lightmicroscope,_____organelles are visible in_____eukaryotes.
19. At the end ofits”life,”______mRNA molecule is degraded.
20. ______first probe was chosenupstream of _____Cal sequence.
21. _____NbCAl promoter was amplifiedusing_____BD Genome Walker Universal Kit(BD Bioscience-Clontech,Palo Alto,CA).
22. ______experimental data show_____stronginterference pattern that qualitatively resembles the pattern induced by adouble slit.
参考答案
1. Oscillatory behavior wasreduced in the presence of a ringelectrode.
2. Sea urchin fertilization is a/the model system in developmentalbiology. (a—多个model system；the—唯一的model system.)
3. Therefore, the hypothesis we presented previously is further confirmed.
4. Back to nature.
5. Inorganic chemistry proves tobe a very interesting subject.
6. Can you name an inorganic molecule?
7. Conversion of a/the CK riboside to the base can beregarded as the last step. (a—多个CK；the—唯一的CK.)
8. The data for oxidation ofhydrogen at the Pt electrode were obtained in the absence of chloride ions.
9. The theoretical studies cited earlier depict a variety of differentpatterns in oscillating media.
10. Here we discuss (the) physical-chemical mechanismsleading to pattern formation in electrochemical systems.
11. Title: Role of Physical Activity on the Severity of Diabetes
12. Title: Orbital Reconstruction and Covalent Bonding at an Oxide Interface
13. Title: Correlation of theHighest-Energy Cosmic Rays with Nearby Extragalactic Objects
14. Figure 4: Effect of temperature on ctx expression.
15. Lichens consist of algae (orcyanobacteria) and fungi, which coexist in symbiosis.
16. Rainfall in the Sahara desert occurs rarely.
17. The average rainfall in theSahara desert is less than 25 mmper year.
18. Under the light microscope, organdies are visible in eukaryotes.
19. At the end of its “life”, an mRNA molecule is degraded.
20. The first probe was chosen upstream of the CA 1 sequence.
21. The NbCA1 promoter was amplified using the BD GenomeWalker Universal Kit (BD Bioscience-Clontech, PaloAlto, CA).
22. The experimental data show astrong interference pattern that qualitatively resembles the pattern induced bya double slit.
摘编自《科技写作与交流》(任胜利等译. 科学出版社,2012年出版)
