单项选择题
In the quest to find a __________ for cancer, scientists must draw on a collective information base.
单项选择题 He __________ his repeated failures to the bad luck and unfavorable financial conditions.
单项选择题 The __________ of forged banknotes posed a threat to our normal economic life.
单项选择题 An individual nerve cell usually has a large cell body and a __________ nucleus.
