Some time ago I discovered one of my chairs had a broken leg. I think it is easy to get it mended, as there are many antique (古董) shops around my flat.
But I was quite wrong. When I went into the first shop with the chair, the man refused to mend it for me. I wasn’t too concerned (担心的). After all, it was only the first try. The reaction (反应) at the second shop was just the same, and at the third.
I entered the fourth shop with confidence because I had made up a plan. I put down the chair and asked if they wanted to buy it. The assistant looked it over carefully and said, "Yes, not a bad little chair. How much do you want for it" "￡25," I said, "It’s got a slightly broken leg." "Yes, I saw. Don’t worry about it."
"What will you do with it" I asked. "Oh, it will be very saleable once repaired." "I’ll buy it," I said. "But you’ve just sold it to me," he said. "Yes, but I’ve changed my mind; in fact it is just what I’m looking for—I’ve got a pair to it at home. I’ll give you 30 pounds for it." "You must be crazy," he said; then suddenly the penny dropped and he smiled and said, "I know you want me to mend your chair."
"And what would you have done, if I had walked in and said ’Would you mend this chair for me’" "I wouldn’t have done it," he said, "We don’t do repairs, not enough money in it, but I’ll mend this for you." The phrase "the penny dropped" (line 4, para.4) means ______.