As for the national debt, the benefits of immigration are only likely to accrue with time. Later generations of immigrants tend to pay more in taxes as educational attainment and incomes rise, according to the Cato Institute’s report, which called children of immigrants “the most potent fiscal engine this country has ever seen.” Should Trump’s immigration crackdown cause a sustained decline in new entries, that engine will be much less powerful than it could have been.
int key = arr[i]; // 待插入的元素
。关于这个话题，搜狗输入法下载提供了深入分析
（一）为他人提供取款、转移运送现金等服务的；
Source: Computational Materials Science, Volume 266