【正确答案】:
MANY CHILDREN WERE PLAYING CLOSE TO THE TRACKS THEN, AND WE WERE STUNNED BY THEIR IGNORANCE AND DARING. 
【题目解析】:close表示地理方位上的近。用在此处形容孩子们离得近更合适。closely形容密切地,在这里不合适。
MANY CHILDREN WERE PLAYING CLOSE TO THE TRACKS THEN, AND WE WERE STUNNED BY THEIR IGNORANCE AND DARING.