37. "An ounce of prevention is worth a pound of cure."
38. "You never miss the water till the well runs dry."
39. "Penny wise, pound foolish."
40. Select any proverb. Explain it.
41. Choose a short quotation from some poem. Explain it.
42. Explain some technical operation.
43. Explain some mechanical process.
44. A range factory.
45. Making electric bulbs.
46. How moving pictures are made and reproduced.