阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。
Several weeks ago, my husband and I decided to sell some of the old things in our house. We thought              a good opportunity to clean up our 10-year-old son’s room and deal with some toys that were no             (long) suitable for him to play with. We agreed that all the money          (make) from selling the toys would go to our son.
We decided to sell the toys our son no longer liked and a little bike that was too small for him. The little bike,            a bit old, was still in good condition.
We charged $ 10 for the bike,             it didn’t sell. So, after the sale was over, my husband put it on the roadside with a sign, on          were written “FREE BIKE”. Soon our doorbell rang. A little boy stood outside,            (ask) in poor English whether the bike was really free. I said yes and that he could have it           nothing. He smiled, got on the bike and            (happy) rode away.
Later that evening I told my son that the old bike had been given to the little boy for free. He smiled, obviously happy             (hear) that someone else would make good use of that little bike.