Thus he became the supreme propagandist of science and his name the great symbol of an almost blind faith in its possibilities. Thirty years ago, when I was a schoolboy, the ancient conservatism of man was still the normal inheritance of every child. We began to have electric lights, and telephones, and to see horseless carriages, but our attitude was a mixture of wonder, fear, and doubt. Perhaps these things would work. Perhaps they would not explode. Perhaps it would be amusing to play with them.

 it would be amusing to play with them. 这里为什么用过去将来进行时态？