GUNPOWDER, IN SOME WAYS THE MOST EFFECTIVE OF ALL THE EXPLOSIVE MA...
21. Gunpowder, in some ways the most effective of all the explosive materials,
……….. a mixture of potassium nitrate, charcoal, and sulfur.
a. were
b. had been
c. had
d. was
d
21. Gunpowder, in some ways the most effective of all the explosive materials,
……….. a mixture of potassium nitrate, charcoal, and sulfur.
a. were
b. had been
c. had
d. was
d