单项选择题According to this passage, chemistry ______.
单项选择题The underlined word tainted in the first paragraph most probably means ______.
单项选择题The third paragraph is mainly about ______.
单项选择题According to the passage, which of the following is a true statement, about sectional conflicts in America between 1763 and 1789
单项选择题According to the passage, Loyalism during the American Revolutionary War served the function of ______.