【单选题】Directions: Choose the right one from the four choices marked A, B, C or D. Some animal studies suggest that ascorbic acid may _____ lead and decrease the risk of the toxic effects of lead.
【简答题】The argument that humans, even in prehistoric times, had some number sense, at least to the extent of recognizing the concepts of more and less when some objects were added to or taken away from a sma...