题目内容：

make a purchase在这里什么意思?
When people click on those links from your ebook to the sites that you are promoting and make a purchase, you make money.
把这句话也翻译一下
购买？购买网站？不通阿。感觉应该是自己帮忙推广的网站之间的关系（顺便说一下电子书是免费的）