There is evidence that DHA plays a big role in the intellectual development of humans. In one study, doctors measured the DHA levels of mothers at the time they __56___. Their children were then tested at 12 and 18 months of age to see how well they __57___ things around them. The research team compiled data on __58___ each child focused on a toy. The toddlers ___59__ mothers had the highest DHA levels at birth showed the greatest attention spans. These children focused for longer periods and spent much less time simply ___60__, unfocused. 【題組】57. (A) being paid attention (B) paid attention to (C) were paid attention (D) were paid attention to