foreign resident tests in order to qualify for certain exclusions a US citizen must meet either bona fide resident or physical present test

a. define both of these tests

b. may a US citizen qualify under either or bot of these tests even though the citizen owns a home in US and expects to return to that home permanetely at the end of 3 years?

cmay a US citizen who lives in 3 different countries during a 2 year period qualify under either or both tests?