Answers

7. When the preceding while loop ends, the loop condition must be false, that is,
   iFirst >= first.length or iSecond >= second.length (De Morgan's Law).
   Then first.length - iFirst <= 0 or iSecond.length - iSecond <= 0.
8. First sort 8 7 6 5.
   Recursively, first sort 8 7.
   Recursively, first sort 8. It's sorted.
   Sort 7. It's sorted.
   Merge them: 7 8.
   Do the same with 6 5 to get 5 6.
   Merge them to 5 6 7 8.
   Do the same with 4 3 2 1: Sort 4 3 by sorting 4 and 3 and merging them to 3 4.
   Sort 2 1 by sorting 2 and 1 and merging them to 1 2.
   Merge 3 4 and 1 2 to 1 2 3 4.
   Finally, merge 5 6 7 8 and 1 2 3 4 to 1 2 3 4 5 6 7 8.