Together, these two pigments account for just about every color you might see on the skin of mammals: white, red, yellow, brown, and black and every shade in between.

二者混合可呈现你能见到的各种哺乳动物的皮肤颜色：白色、黄色、棕色、黑色和他们之间的过渡色。

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Nonetheless, in a recent study by Harvard's Richard Murnane and co-authors, differences in mother-child interaction patterns like these were found to account for one-third of the black-white gap in math and English skills at the beginning of kindergarten -- and one-quarter at the end of third grade.

CNN: Commentary: What parents can do for their kids