Next, since the searches take place in an asynchronous fashion, we must submit a search, wait for the result callback, check for the terminating condition, and then submit another search.

• 其次,由于搜索是以异步方式进行的,所以我们必须提交一个搜索、等待结果回调、检查中止条件、然后提交另一个搜索。