精选优质文档-倾情为你奉上Unit 1 The Roots of ChemistryI. Comprehension.1.C 2. B 3. D 4. C 5. BII. Make a sentence out of each item by rearranging the words in brackets.1. The purification of an organic compound is usually a matter of considerable difficulty, and it is necessary to employ various methods for this purpose.2. Science is an ever-increasing body of accumulated and systematized knowledge and is also an activity by which knowledge is generated.3. Life, after all, is only
