How had the country existed half-slave and half-free for so many years, Lincoln asked.

VOA: special.2009.06.11

So studying the organisms in these oxygen-free caves gives clues about the past.

VOA: special.2010.11.10

So is cigarette smuggling. Smugglers stock up on cigarettes in low-tax states or buy them tax-free on Indian reservations.

VOA: standard.2010.08.11