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。
When he was a little boy, Christopher Cockerell once noticed his mother turning the wheel of her sewing machine with her hand. “Won’t it work quickly if a machine      (turn) the wheel for you?” he asked. “I suppose it will.” said his mother, without paying any attention to him. Christopher knew she always had a lot of work and that she was       stubborn that he could hardly do anything to change       mind. But he wanted to help. In his bedroom there was a toy steam engine       (buy) by his father as a gift to him. “I will make better use of it,” little Christopher said to himself. So, when his mother was not using her sewing machine, he decided to fix the toy steam engine onto it. When he finished    (do) it, he was quite pleased, thinking his mother would like it. “Very clever,” his mother said when she saw it. But then she sat down and went on turning the wheel     hand. “I     (work) like this for too many years,” she explained. Christopher felt very      (disappoint). He couldn’t understand his mother’s     (behave).
This teaches Christopher a lesson that anyone      tries to improve anything has to learn: many people don’t like new ideas.