缩写自 substitute,代替，替代。

1. Residents in general are poor and undereducated, and live in sub-standard housing.

居民们普遍都很贫穷，受教育程度低，居住条件较差。

2. Men carrying sub-machine guns seized the five soldiers and drove them away.

持冲锋枪的几名男子俘虏了5名士兵并开车将他们带走。

3. The big losers will be the undeveloped countries, especially sub-Saharan Africa.

受害最深的将是不发达国家，尤其是非洲撒哈拉沙漠以南地区。

4. Several other sub-species of gull are found in the region.

在该地区还发现了海鸥的其他亚种。

5. They're armed with sub-machine-guns or machine-pistols or whatever you call those things.

他们持有轻机枪或者冲锋枪，还是什么玩意儿的。