单项选择题The relatively low income of the commercial farmers is mainly caused by ______.
单项选择题According to the passage, which of the following statements is CORRECT
单项选择题As can be gathered from the passage, Aristotle's theories ______ in the Middle Ages.
单项选择题Which of the following is common to Roger Bacon, Francis Bacon and Descartes
单项选择题If refrigerated, USDA eggs will remain good for ______ weeks from the date stamped.