【简答题】Look at Marion's letter and write the order in which the following parts of an informal letter appear. a. Greeting b. Address c. Closing paragraph d. Date e. Middle paragraphs f. Signature ending g. O...
【简答题】The unit of parts per million (ppm) and parts per billion (ppb) are commonly used by environmental chemistrs. In general, 1 ppm means 1 part of solute for every parts of solution. Mathematically, by m...