| 1. | Freckles are simply concentrations of melanin .
雀斑不过是高浓度的黑色素。 |
| 2. | The colon is the locus of a large concentration of bacteria .
结肠是大浓度的细菌所在地。 |
| 3. | The altitude of the peak concentration was lowest in the summer .
在夏季，峰值浓度的高度为最低。 |
| 4. | It also contains high concentrations of proline and hydroxyproline .
它还含有高浓度的脯氨酸和羟脯氨酸。 |
| 5. | The electrolyte within the glass electrode is an acid solution of definite strength .
玻璃电极中的电解质是具有一定浓度的酸溶液。 |
| 6. | It is necessary to enrich the fuel by increasing the percentage concentration of uranium-235 .
必须提高铀235浓度的百分比，使燃料浓集。 |
| 7. | Once the desired specific gravity is established, the same strength must be used henceforth .
所需的比重一经确定，以后就必须使用同一浓度的酸。 |
| 8. | In order to overcome this deficiency, the concept of activity or effective concentration was advanced .
为了克服这一缺点，提出了活度或有效浓度的概念。 |
| 9. | Depletion of soil nitrogen frequently leads to reduced concentrations of soluble amino and amides .
土壤氮素的减少常常导致可溶性氨基酸和酰胺浓度的降低。 |
| 10. | Atomic absorption spectroscopy has proved to be a versatile tool in measuring concentrations of trace metals .
原子吸收光谱法已证明是一种用于测定痕量的金属浓度的灵活多用的仪器。 |
