In 1492 Columbus and his crew arrived ______ was so-called the New World by the westerners．

.On April Fool’s Day people often play tricks _____ others.

Evidence obtained from observation and experiment is often used to _____ a scientific theory.

Nobody would stand out admitting the fact, for some reason,      they lost the game.

.He suffered from a serious illness last year and I don’t know whether he is_____or dead now.