Intheoriginaltest，alltheanimalsinatestgrouparegivenasubstance_______halfofthemdie
B
本题考查词义辨析。 until：直到。符合句意，表示 given a substance 持续到 half of them die 。
In 1950,one of the leading American writers( )was awarded the Nobel Prize for the anti-racist Intruder in the Dust.
After the American Civil War,the literary interest in the so- called “reality ” of life started a new period in the American literary writings know an the Age of( ).
In 1950,( )was awarded the Nobel Prize for the anti-racist Intruder in the Dust.
Unlikehiscontemporariesintheearly20thcentury,()didnotbreakupwiththepoetictraditionnormadeanyexperimentonform.