... (D. what) the speaker has said. 17. Gunpowder, (A. in some ways) (B. the most effective) of (C. all) the explosive materials, (D. were) a mixture of potassium nitrate, charcoal, and sulfur. 18. ... Sheet 1 A) 2 C) 3 C) 4 B) 5 B) 6 C) 7 A) 8 A) 9 A) 10 C) 11 C) 12 C) 13 D) 14 D) 15 C) 16 B) 17 D) 18 B) 19 B) 20 A) 21 B) 22 A) 23 B) 24 A) 25 D) 26 A) 27 D) 28 A) 29 B) 30 D) 31 A) 32 D)...