语法与词汇 Even before an infant is born, tiny teeth are developing (within) his gums.
【正确答案】 B
【答案解析】inside“在…里”。behind“在…之后”；in front of“在…之前”；next to“在…附近，紧挨着”。本题译文：甚至在婴儿出生前，小牙齿就在牙龈里生长了。