13. What is a diphthong?
14. What is a digraph?
15. What are the two sounds each of c, g, de, th, and s? Give examples of each.
16. How many letters are there in the English alphabet and how many sounds do they express?
17. Upon what does correct pronunciation depend?
18. What is a syllable, and of what does it consist?
19. What peculiar use is made of l and n in English?
20. How do we treat the parts of a diphthong or digraph?
21. How do we know whether or not these compounds are diphthongs or digraphs?
22. What about vowel combinations?